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Amino acid

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Organic compounds containing amine and carboxylic groups

The structure of an alpha amino acid in its un-ionized form

Amino acids are

organic compounds

that contain

amino

(–NH2) and

carboxyl

(–COOH)

functional groups

, along with a

side chain

(R group) specific to each amino acid.

[1]

[2]

The key

elements

of an amino acid are

carbon

(C),

hydrogen

(H),

oxygen

(O), and

nitrogen

(N), although other elements are found in the side chains of certain amino acids. About 500 naturally occurring amino acids are known as of 1983 (though only 20 appear in the

genetic code

) and can be classified in many ways.

[3]

They can be classified according to the core structural functional groups’ locations as

alpha- (α-), beta- (β-), gamma- (γ-) or delta- (δ-)

amino acids; other categories relate to

polarity

,

pH

level, and side chain group type (

aliphatic

,

acyclic

,

aromatic

, containing

hydroxyl

or

sulfur

, etc.). In the form of

proteins

, amino acid

residues

form the second-largest component (

water

is the largest) of human

muscles

and other

tissues

.

[4]

Beyond their role as residues in proteins, amino acids participate in a number of processes such as

neurotransmitter

transport and

biosynthesis

.

In

biochemistry

, amino acids which have the amine group attached to the

(alpha-) carbon

atom next to the carboxyl group have particular importance. They are known as 2-, alpha-, or α-amino acids (generic

formula

H2NCHRCOOH in most cases,

[a]

where R is an

organic

substituent

known as a “

side chain

“);

[5]

often the term “amino acid” is used to refer specifically to these. They include the 22

proteinogenic

(“protein-building”) amino acids,

[6]

[7]

[8]

which combine into

peptide

chains (“polypeptides”) to form the building blocks of a vast array of

proteins

.

[9]

These are all L

stereoisomers

(“

left-handed

isomers

), although a few D-amino acids (“right-handed”) occur in

bacterial envelopes

, as a

neuromodulator

(D

serine

), and in some

antibiotics

.

[10]

Twenty of the proteinogenic amino acids are encoded directly by triplet

codons

in the

genetic code

and are known as “standard” amino acids. The other two (“nonstandard” or “non-canonical”) are

selenocysteine

(present in many

prokaryotes

as well as most

eukaryotes

, but not coded directly by

DNA

), and

pyrrolysine

(found only in some

archaea

and one

bacterium

). Pyrrolysine and selenocysteine are encoded via variant codons; for example, selenocysteine is encoded by

stop codon

and

SECIS element

.

[11]

[12]

[13]

N-formylmethionine

(which is often the initial amino acid of proteins in bacteria,

mitochondria

, and

chloroplasts

) is generally considered as a form of

methionine

rather than as a separate proteinogenic amino acid. Codon–

tRNA

combinations not found in nature can also be used to

“expand” the genetic code

and form novel proteins known as

alloproteins

incorporating

non-proteinogenic amino acids

.

[14]

[15]

[16]

Many important proteinogenic and non-proteinogenic amino acids have biological functions. For example, in the

human brain

, glutamate (standard

glutamic acid

) and

gamma-aminobutyric acid

(“GABA”, nonstandard gamma-amino acid) are, respectively, the main

excitatory and inhibitory neurotransmitters

.

[17]

Hydroxyproline

, a major component of the

connective tissue

collagen

, is synthesised from

proline

.

Glycine

is a biosynthetic precursor to

porphyrins

used in

red blood cells

.

Carnitine

is used in

lipid transport

. Nine proteinogenic amino acids are called “

essential

” for humans because they cannot be produced from other

compounds

by the human body and so must be taken in as food. Others may be

conditionally essential

for certain ages or medical conditions. Essential amino acids may also vary from

species

to species.

[b]

Because of their biological significance, amino acids are important in nutrition and are commonly used in

nutritional supplements

,

fertilizers

,

feed

, and

food technology

. Industrial uses include the production of

drugs

,

biodegradable plastics

, and

chiral catalysts

.

History[

edit

]

The first few amino acids were discovered in the early 19th century.

[18]

[19]

In 1806, French chemists

Louis-Nicolas Vauquelin

and

Pierre Jean Robiquet

isolated a compound in

asparagus

that was subsequently named

asparagine

, the first amino acid to be discovered.

[20]

[21]

Cystine

was discovered in 1810,

[22]

although its monomer,

cysteine

, remained undiscovered until 1884.

[21]

[23]

Glycine

and

leucine

were discovered in 1820.

[24]

The last of the 20 common amino acids to be discovered was

threonine

in 1935 by

William Cumming Rose

, who also determined the

essential amino acids

and established the minimum daily requirements of all amino acids for optimal growth.

[25]

[26]

The unity of the chemical category was recognized by

Wurtz

in 1865, but he gave no particular name to it.

[27]

The first use of the term “amino acid” in the English language dates from 1898,

[28]

while the German term, Aminosäure, was used earlier.

[29]

Proteins were found to yield amino acids after enzymatic digestion or acid

hydrolysis

. In 1902,

Emil Fischer

and

Franz Hofmeister

independently proposed that proteins are formed from many amino acids, whereby bonds are formed between the amino group of one amino acid with the carboxyl group of another, resulting in a linear structure that Fischer termed “

peptide

“.

[30]

General structure[

edit

]

The 21

proteinogenic α-amino acids

found in

eukaryotes

, grouped according to their side chains’

pKa

values and charges carried at

physiological pH (7.4)

In the structure shown at the top of the page, R represents a

side chain

specific to each amino acid. The

carbon

atom next to the

carboxyl group

is called the

α–carbon

. Amino acids containing an

amino group

bonded directly to the alpha carbon are referred to as alpha amino acids.

[31]

These include amino acids such as

proline

which contain

secondary amines

, which used to be often referred to as “imino acids”.

[32]

[33]

[34]

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Isomerism[

edit

]

Alpha-amino acids are the common natural forms of amino acids. With the exception of

glycine

, other natural amino acids adopt the L configuration.

[35]

While L-amino acids represent all of the amino acids found in

proteins

during translation in the ribosome.

The L and D convention for amino acid configuration refers not to the optical activity of the amino acid itself but rather to the optical activity of the isomer of

glyceraldehyde

from which that amino acid can, in theory, be synthesized (D-glyceraldehyde is dextrorotatory; L-glyceraldehyde is levorotatory). In alternative fashion, the

(S) and (R) designators

are used to indicate the absolute configuration. Almost all of the amino acids in proteins are (S) at the α carbon, with

cysteine

being (R) and

glycine

non-

chiral

.

[36]

Cysteine has its side chain in the same geometric location as the other amino acids, but the R/S terminology is reversed because

sulfur

has higher atomic number compared to the carboxyl oxygen which gives the side chain a higher priority by the

Cahn-Ingold-Prelog sequence rules

, whereas the atoms in most other side chains give them lower priority compared to the carboxyl group.[

citation needed

]

D-amino acid residues

are found in some proteins, but they are rare.

Side chains[

edit

]

Amino acids are designated as α- when the nitrogen atom is attached to the carbon atom adjacent to the carboxyl group: in this case the compound contains the substructure N–C–CO2. Amino acids with the sub-structure N–C–C–CO2 are classified as β- amino acids. γ-Amino acids contain the substructure N–C–C–C–CO2, and so on.

[37]

Amino acids are usually classified by the

properties

of their side chain into four groups. The side chain can make an amino acid a

weak acid

or a

weak base

, and a

hydrophile

if the side chain is

polar

or a

hydrophobe

if it is

nonpolar

.

[35]

The phrase “

branched-chain amino acids

” or BCAA refers to the amino acids having

aliphatic

side chains that are linear; these are

leucine

,

isoleucine

, and

valine

.

Proline

is the only

proteinogenic

amino acid whose side-group links to the α-amino group and, thus, is also the only proteinogenic amino acid containing a secondary amine at this position.

[35]

In chemical terms, proline is, therefore, an

imino acid

, since it lacks a

primary amino group

,

[38]

although it is still classed as an amino acid in the current biochemical nomenclature

[39]

and may also be called an “N-alkylated alpha-amino acid”.

[40]

Zwitterions[

edit

]

An amino acid in its (1) molecular and (2) zwitterionic forms

In aqueous solution amino acids exist in two forms (as illustrated at the right), the molecular form and the

zwitterion

form in equilibrium with each other. The two forms coexist over the pH range pK1 − 2 to pK2 + 2, which for glycine is pH 0–12. The ratio of the concentrations of the two isomers is independent of pH. The value of this ratio cannot be determined experimentally.

Because all amino acids contain amine and carboxylic acid functional groups, they are

amphiprotic

.

[35]

At pH = pK1 (approximately 2.2) there will be equal concentration of the species NH+
3
CH(R)CO
2
H
and NH+
3
CH(R)CO
2
and at pH = pK2 (approximately 10) there will be equal concentration of the species NH+
3
CH(R)CO
2
and NH
2
CH(R)CO
2
. It follows that the neutral molecule and the zwitterion are effectively the only species present at biological pH.

[41]

It is generally assumed that the concentration of the zwitterion is much greater than the concentration of the neutral molecule on the basis of comparisons with the known pK values of

amines

and

carboxylic acids

.

Isoelectric point[

edit

]

Composite of

titration curves

of twenty proteinogenic amino acids grouped by side chain category

At pH values between the two pKa values, the zwitterion predominates, but coexists in

dynamic equilibrium

with small amounts of net negative and net positive ions. At the exact midpoint between the two pKa values, the trace amount of net negative and trace of net positive ions exactly balance, so that average net charge of all forms present is zero.

[42]

This pH is known as the

isoelectric point

pI, so pI = 1/2(pKa1 + pKa2). For amino acids with charged side chains, the pKa of the side chain is involved. Thus for aspartate or glutamate with negative side chains, pI = 1/2(pKa1 + pKa(R)), where pKa(R) is the side chain pKa. Cysteine also has potentially negative side chain with pKa(R) = 8.14, so pI should be calculated as for aspartate and glutamate, even though the side chain is not significantly charged at physiological pH. For histidine, lysine, and arginine with positive side chains, pI = 1/2(pKa(R) + pKa2). Amino acids have zero mobility in electrophoresis at their isoelectric point, although this behaviour is more usually exploited for peptides and proteins than single amino acids. Zwitterions have minimum solubility at their isoelectric point, and some amino acids (in particular, with nonpolar side chains) can be isolated by precipitation from water by adjusting the pH to the required isoelectric point.

Occurrence and functions in biochemistry[

edit

]

A protein depicted as a long unbranched string of linked circles each representing amino acids

A

polypeptide

is an unbranched chain of amino acids

Diagrammatic comparison of the structures of β-alanine and α-alanine

β-Alanine and its α-alanine isomer

A diagram showing the structure of selenocysteine

The amino acid

selenocysteine

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Proteinogenic amino acids[

edit

]

Amino acids are the structural units (

monomers

) that make up proteins. They join together to form short

polymer

chains called

peptides

or longer chains called either

polypeptides

or

proteins

. These chains are linear and unbranched, with each amino acid residue within the chain attached to two neighboring amino acids. The process of making proteins encoded by DNA/RNA genetic material is called

translation

and involves the step-by-step addition of amino acids to a growing protein chain by a

ribozyme

that is called a

ribosome

.

[43]

The order in which the amino acids are added is read through the

genetic code

from an

mRNA

template, which is an

RNA

copy of one of the organism’s

genes

.

Twenty-two amino acids are naturally incorporated into polypeptides and are called

proteinogenic

or natural amino acids.

[35]

Of these, 20 are encoded by the universal

genetic code

. The remaining 2,

selenocysteine

and

pyrrolysine

, are incorporated into proteins by unique synthetic mechanisms.

Selenocysteine

is incorporated when the mRNA being translated includes a

SECIS element

, which causes the UGA codon to encode selenocysteine instead of a

stop codon

.

[44]

Pyrrolysine

is used by some

methanogenic

archaea

in enzymes that they use to produce

methane

. It is coded for with the codon UAG, which is normally a stop codon in other organisms.

[45]

This UAG codon is followed by a

PYLIS downstream sequence

.

[46]

Several independent evolutionary studies, using different types of data, have suggested that Gly, Ala, Asp, Val, Ser, Pro, Glu, Leu, Thr (i.e. G, A, D, V, S, P, E, L, T) may belong to a group of amino acids that constituted the early genetic code, whereas Cys, Met, Tyr, Trp, His, Phe (i.e. C, M, Y, W, H, F) may belong to a group of amino acids that constituted later additions of the genetic code.

[47]

[48]

[49]

[50]

Non-proteinogenic amino acids[

edit

]

Aside from the 22

proteinogenic amino acids

, many non-proteinogenic amino acids are known. Those either are not found in proteins (for example

carnitine

,

GABA

,

levothyroxine

) or are not produced directly and in isolation by standard cellular machinery (for example,

hydroxyproline

and

selenomethionine

).

Non-proteinogenic amino acids that are found in proteins are formed by

post-translational modification

, which is modification after translation during protein synthesis. These modifications are often essential for the function or regulation of a protein. For example, the

carboxylation

of

glutamate

allows for better binding of

calcium cations

,

[51]

and

collagen

contains hydroxyproline, generated by

hydroxylation

of

proline

.

[52]

Another example is the formation of

hypusine

in the

translation initiation factor

EIF5A

, through modification of a lysine residue.

[53]

Such modifications can also determine the localization of the protein, e.g., the addition of long hydrophobic groups can cause a protein to bind to a

phospholipid

membrane.

[54]

Some non-proteinogenic amino acids are not found in proteins. Examples include

2-aminoisobutyric acid

and the neurotransmitter

gamma-aminobutyric acid

. Non-proteinogenic amino acids often occur as intermediates in the

metabolic pathways

for standard amino acids – for example,

ornithine

and

citrulline

occur in the

urea cycle

, part of amino acid

catabolism

(see below).

[55]

A rare exception to the dominance of α-amino acids in biology is the β-amino acid

beta alanine

(3-aminopropanoic acid), which is used in plants and microorganisms in the synthesis of

pantothenic acid

(vitamin B5), a component of

coenzyme A

.

[56]

Nonstandard amino acids[

edit

]

The 20 amino acids that are encoded directly by the codons of the universal

genetic code

are called standard or canonical amino acids. A modified form of methionine (

N-formylmethionine

) is often incorporated in place of methionine as the initial amino acid of proteins in bacteria, mitochondria and chloroplasts. Other amino acids are called nonstandard or non-canonical. Most of the nonstandard amino acids are also non-proteinogenic (i.e. they cannot be incorporated into proteins during translation), but two of them are proteinogenic, as they can be incorporated translationally into proteins by exploiting information not encoded in the universal genetic code.

The two nonstandard proteinogenic amino acids are

selenocysteine

(present in many non-eukaryotes as well as most eukaryotes, but not coded directly by DNA) and

pyrrolysine

(found only in some

archaea

and at least one

bacterium

). The incorporation of these nonstandard amino acids is rare. For example, 25 human proteins include selenocysteine in their primary structure,

[57]

and the structurally characterized enzymes (selenoenzymes) employ selenocysteine as the catalytic

moiety

in their active sites.

[58]

Pyrrolysine and selenocysteine are encoded via variant codons. For example, selenocysteine is encoded by

stop codon

and

SECIS element

.

[11]

[12]

[13]

In human nutrition[

edit

]

Diagram showing the relative occurrence of amino acids in blood serum as obtained from diverse diets.

Share of amino acid in various human diets and the resulting mix of amino acids in human blood serum. Glutamate and glutamine are the most frequent in food at over 10%, while alanine, glutamine, and glycine are the most common in blood.

When taken up into the human body from the diet, the 20 standard amino acids either are used to synthesize proteins, other biomolecules, or are oxidized to

urea

and

carbon dioxide

as a source of energy.

[59]

The oxidation pathway starts with the removal of the amino group by a

transaminase

; the amino group is then fed into the

urea cycle

. The other product of transamidation is a

keto acid

that enters the

citric acid cycle

.

[60]

Glucogenic amino acids

can also be converted into glucose, through

gluconeogenesis

.

[61]

Of the 20 standard amino acids, nine (

His

,

Ile

,

Leu

,

Lys

,

Met

,

Phe

,

Thr

,

Trp

and

Val

) are called

essential amino acids

because the

human body

cannot

synthesize

them from other

compounds

at the level needed for normal growth, so they must be obtained from food.

[62]

[63]

[64]

In addition,

cysteine

,

tyrosine

, and

arginine

are considered semiessential amino acids, and taurine a semiessential aminosulfonic acid in children. The metabolic pathways that synthesize these monomers are not fully developed.

[65]

[66]

The amounts required also depend on the age and health of the individual, so it is hard to make general statements about the dietary requirement for some amino acids. Dietary exposure to the nonstandard amino acid

BMAA

has been linked to human neurodegenerative diseases, including

ALS

.

[67]

[68]

Signaling cascade diagram

Diagram of the molecular

signaling cascades

that are involved in

myofibrillar

muscle protein synthesis and

mitochondrial biogenesis

in response to physical exercise and specific amino acids or their derivatives (primarily

L-leucine

and

HMB

).

[69]

Many amino acids derived from food protein promote the activation of

mTORC1

and increase

protein synthesis

by

signaling

through

Rag GTPases

.

[69]

[70]

Abbreviations and representations:
 • PLD:

phospholipase D

 • PA:

phosphatidic acid

 • mTOR:

mechanistic target of rapamycin

 • AMP:

adenosine monophosphate

 • ATP:

adenosine triphosphate

 • AMPK:

AMP-activated protein kinase

 • PGC‐1α:

peroxisome proliferator-activated receptor gamma coactivator-1α

 • S6K1:

p70S6 kinase

 • 4EBP1:

eukaryotic translation initiation factor 4E-binding protein 1

 • eIF4E:

eukaryotic translation initiation factor 4E

 • RPS6:

ribosomal protein S6

 • eEF2:

eukaryotic elongation factor 2

 • RE: resistance exercise; EE: endurance exercise
 • Myo:

myofibrillar

; Mito:

mitochondrial

 • AA: amino acids
 • HMB:

β-hydroxy β-methylbutyric acid

 • ↑ represents activation
 • Τ represents inhibition

Graph of muscle protein synthesis vs time

Resistance training stimulates muscle protein synthesis (MPS) for a period of up to 48 hours following exercise (shown by lighter dotted line).

[71]

Ingestion of a protein-rich meal at any point during this period will augment the exercise-induced increase in muscle protein synthesis (shown by solid lines).

[71]

Non-protein functions[

edit

]

Biosynthetic pathways for

catecholamines

and

trace amines

in the

human brain

[72]

[73]

[74]

Graphic of catecholamine and trace amine biosynthesis

L-Phenylalanine

L-Tyrosine

L-DOPA

Epinephrine

Phenethylamine

p-Tyramine

Dopamine

Norepinephrine

N-Methylphenethylamine

N-Methyltyramine

p-Octopamine

Synephrine

3-Methoxytyramine

AADC

AADC

AADC

primary
pathway

PNMT

PNMT

PNMT

PNMT

AAAH

AAAH

brain

CYP2D6

minor
pathway

COMT

DBH

DBH

The image above contains clickable links

Catecholamines

and

trace amines

are synthesized from phenylalanine and tyrosine in humans.

In humans, non-protein amino acids also have important roles as

metabolic intermediates

, such as in the biosynthesis of the

neurotransmitter

gamma-aminobutyric acid

(GABA). Many amino acids are used to synthesize other molecules, for example:

  • Tryptophan

    is a precursor of the neurotransmitter

    serotonin

    .

    [75]

  • Tyrosine

    (and its precursor phenylalanine) are precursors of the

    catecholamine

    neurotransmitters

    dopamine

    ,

    epinephrine

    and

    norepinephrine

    and various

    trace amines

    .

  • Phenylalanine

    is a precursor of

    phenethylamine

    and tyrosine in humans. In plants, it is a precursor of various

    phenylpropanoids

    , which are important in plant metabolism.

  • Glycine

    is a precursor of

    porphyrins

    such as

    heme

    .

    [76]

  • Arginine

    is a precursor of

    nitric oxide

    .

    [77]

  • Ornithine

    and

    S-adenosylmethionine

    are precursors of

    polyamines

    .

    [78]

  • Aspartate

    ,

    glycine

    , and

    glutamine

    are precursors of

    nucleotides

    .

    [79]

    However, not all of the functions of other abundant nonstandard amino acids are known.

Some nonstandard amino acids are used as

defenses against herbivores

in plants.

[80]

For example,

canavanine

is an analogue of

arginine

that is found in many

legumes

,

[81]

and in particularly large amounts in

Canavalia gladiata

(sword bean).

[82]

This amino acid protects the plants from predators such as insects and can cause illness in people if some types of legumes are eaten without processing.

[83]

The non-protein amino acid

mimosine

is found in other species of legume, in particular

Leucaena leucocephala

.

[84]

This compound is an analogue of

tyrosine

and can poison animals that graze on these plants.

Uses in industry[

edit

]

Amino acids are used for a variety of applications in industry, but their main use is as additives to

animal feed

. This is necessary, since many of the bulk components of these feeds, such as

soybeans

, either have low levels or lack some of the

essential amino acids

: lysine, methionine, threonine, and tryptophan are most important in the production of these feeds.

[85]

In this industry, amino acids are also used to chelate metal cations in order to improve the absorption of minerals from supplements, which may be required to improve the health or production of these animals.

[86]

The

food industry

is also a major consumer of amino acids, in particular,

glutamic acid

, which is used as a

flavor enhancer

,

[87]

and

aspartame

(aspartylphenylalanine 1-methyl ester) as a low-calorie

artificial sweetener

.

[88]

Similar technology to that used for animal nutrition is employed in the human nutrition industry to alleviate symptoms of mineral deficiencies, such as anemia, by improving mineral absorption and reducing negative side effects from inorganic mineral supplementation.

[89]

The chelating ability of amino acids has been used in fertilizers for agriculture to facilitate the delivery of minerals to plants in order to correct mineral deficiencies, such as iron chlorosis. These fertilizers are also used to prevent deficiencies from occurring and improving the overall health of the plants.

[90]

The remaining production of amino acids is used in the synthesis of

drugs

and

cosmetics

.

[85]

Similarly, some amino acids derivatives are used in pharmaceutical industry. They include

5-HTP

(5-hydroxytryptophan) used for experimental treatment of depression,

[91]

L-DOPA

(L-dihydroxyphenylalanine) for

Parkinson’s

treatment,

[92]

and

eflornithine

drug that inhibits

ornithine decarboxylase

and used in the treatment of

sleeping sickness

.

[93]

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Expanded genetic code[

edit

]

Since 2001, 40 non-natural amino acids have been added into protein by creating a unique codon (recoding) and a corresponding transfer-RNA:aminoacyl – tRNA-synthetase pair to encode it with diverse physicochemical and biological properties in order to be used as a tool to exploring

protein structure

and function or to create novel or enhanced proteins.

[14]

[15]

Nullomers[

edit

]

Nullomers are codons that in theory code for an amino acid, however in nature there is a selective bias against using this codon in favor of another, for example bacteria prefer to use CGA instead of AGA to code for arginine.

[94]

This creates some sequences that do not appear in the genome. This characteristic can be taken advantage of and used to create new selective cancer-fighting drugs

[95]

and to prevent cross-contamination of DNA samples from crime-scene investigations.

[96]

Chemical building blocks[

edit

]

Amino acids are important as low-cost

feedstocks

. These compounds are used in

chiral pool synthesis

as

enantiomerically pure

building blocks.

[97]

Amino acids have been investigated as precursors

chiral catalysts

, such as for asymmetric

hydrogenation

reactions, although no commercial applications exist.

[98]

Biodegradable plastics[

edit

]

Amino acids have been considered as components of biodegradable polymers, which have applications as

environmentally friendly

packaging and in medicine in

drug delivery

and the construction of

prosthetic implants

.

[99]

An interesting example of such materials is

polyaspartate

, a water-soluble biodegradable polymer that may have applications in disposable

diapers

and agriculture.

[100]

Due to its solubility and ability to

chelate

metal ions, polyaspartate is also being used as a biodegradeable anti

scaling

agent and a

corrosion inhibitor

.

[101]

[102]

In addition, the aromatic amino acid

tyrosine

has been considered as a possible replacement for

phenols

such as

bisphenol A

in the manufacture of

polycarbonates

.

[103]

Synthesis[

edit

]

For the steps in the reaction, see the text.

The Strecker amino acid synthesis

Chemical synthesis[

edit

]

The commercial production of amino acids usually relies on mutant bacteria that overproduce individual amino acids using glucose as a carbon source. Some amino acids are produced by enzymatic conversions of synthetic intermediates.

2-Aminothiazoline-4-carboxylic acid

is an intermediate in one industrial synthesis of

L-cysteine

for example.

Aspartic acid

is produced by the addition of ammonia to

fumarate

using a lyase.

[104]

Xem thêm: Các chất được cấu tạo như thế nào?-Chuyên đề môn Vật lý lớp 8-VnDoc.com

Biosynthesis[

edit

]

In plants, nitrogen is first assimilated into organic compounds in the form of

glutamate

, formed from alpha-ketoglutarate and ammonia in the mitochondrion. For other amino acids, plants use

transaminases

to move the amino group from glutamate to another alpha-keto acid. For example, aspartate aminotransferase converts glutamate and oxaloacetate to alpha-ketoglutarate and aspartate.

[105]

Other organisms use transaminases for amino acid synthesis, too.

Nonstandard amino acids are usually formed through modifications to standard amino acids. For example,

homocysteine

is formed through the

transsulfuration pathway

or by the demethylation of methionine via the intermediate metabolite

S-adenosylmethionine

,

[106]

while

hydroxyproline

is made by a

post translational modification

of

proline

.

[107]

Microorganisms

and plants synthesize many uncommon amino acids. For example, some microbes make

2-aminoisobutyric acid

and

lanthionine

, which is a sulfide-bridged derivative of alanine. Both of these amino acids are found in peptidic

lantibiotics

such as

alamethicin

.

[108]

However, in plants,

1-aminocyclopropane-1-carboxylic acid

is a small disubstituted cyclic amino acid that is an intermediate in the production of the plant hormone

ethylene

.

[109]

Reactions[

edit

]

Amino acids undergo the reactions expected of the constituent functional groups.

[110]

[111]

Peptide bond formation[

edit

]

Two amino acids are shown next to each other. One loses a hydrogen and oxygen from its carboxyl group (COOH) and the other loses a hydrogen from its amino group (NH2). This reaction produces a molecule of water (H2O) and two amino acids joined by a peptide bond (–CO–NH–). The two joined amino acids are called a dipeptide.

The condensation of two amino acids to form a

dipeptide

. The two amino acid residues are linked through a

peptide bond

As both the amine and carboxylic acid groups of amino acids can react to form amide bonds, one amino acid molecule can react with another and become joined through an amide linkage. This

polymerization

of amino acids is what creates proteins. This

condensation reaction

yields the newly formed

peptide bond

and a molecule of water. In cells, this reaction does not occur directly; instead, the amino acid is first activated by attachment to a

transfer RNA

molecule through an

ester

bond. This aminoacyl-tRNA is produced in an

ATP

-dependent reaction carried out by an

aminoacyl tRNA synthetase

.

[112]

This aminoacyl-tRNA is then a substrate for the

ribosome

, which catalyzes the attack of the amino group of the elongating protein chain on the ester bond.

[113]

As a result of this mechanism, all proteins made by ribosomes are synthesized starting at their N-terminus and moving toward their C-terminus.

However, not all peptide bonds are formed in this way. In a few cases, peptides are synthesized by specific enzymes. For example, the tripeptide

glutathione

is an essential part of the defenses of cells against oxidative stress. This peptide is synthesized in two steps from free amino acids.

[114]

In the first step,

gamma-glutamylcysteine synthetase

condenses

cysteine

and

glutamic acid

through a peptide bond formed between the side chain carboxyl of the glutamate (the gamma carbon of this side chain) and the amino group of the cysteine. This dipeptide is then condensed with

glycine

by

glutathione synthetase

to form glutathione.

[115]

In chemistry, peptides are synthesized by a variety of reactions. One of the most-used in

solid-phase peptide synthesis

uses the aromatic oxime derivatives of amino acids as activated units. These are added in sequence onto the growing peptide chain, which is attached to a solid resin support.

[116]

Libraries of peptides are used in drug discovery through

high-throughput screening

.

[117]

The combination of functional groups allow amino acids to be effective polydentate ligands for metal–amino acid chelates.

[118]

The multiple side chains of amino acids can also undergo chemical reactions.

Catabolism[

edit

]

Catabolism of proteinogenic amino acids. Amino acids can be classified according to the properties of their main degradation products:

[119]


* Glucogenic, with the products having the ability to form

glucose

by

gluconeogenesis

* Ketogenic, with the products not having the ability to form glucose. These products may still be used for

ketogenesis

or

lipid synthesis

.
* Amino acids catabolized into both glucogenic and ketogenic products.

Degradation of an amino acid often involves

deamination

by moving its amino group to alpha-ketoglutarate, forming

glutamate

. This process involves transaminases, often the same as those used in amination during synthesis. In many vertebrates, the amino group is then removed through the

urea cycle

and is excreted in the form of

urea

. However, amino acid degradation can produce

uric acid

or ammonia instead. For example,

serine dehydratase

converts serine to pyruvate and ammonia.

[79]

After removal of one or more amino groups, the remainder of the molecule can sometimes be used to synthesize new amino acids, or it can be used for energy by entering

glycolysis

or the

citric acid cycle

, as detailed in image at right.

Complexation[

edit

]

Amino acids are bidentate ligands, forming

transition metal amino acid complexes

.

[120]

AAcomplexation.png

Physicochemical properties of amino acids[

edit

]

The ca. 20 canonical amino acids can be classified according to their properties. Important factors are charge,

hydrophilicity

or

hydrophobicity

, size, and functional groups.

[35]

These properties influence

protein structure

and

protein–protein interactions

. The water-soluble proteins tend to have their hydrophobic residues (

Leu

,

Ile

,

Val

,

Phe

, and

Trp

) buried in the middle of the protein, whereas hydrophilic side chains are exposed to the aqueous solvent. (Note that in

biochemistry

, a residue refers to a specific

monomer

within the

polymeric chain

of a

polysaccharide

,

protein

or

nucleic acid

.) The

integral membrane proteins

tend to have outer rings of exposed

hydrophobic

amino acids that anchor them into the

lipid bilayer

. Some

peripheral membrane proteins

have a patch of hydrophobic amino acids on their surface that locks onto the membrane. In similar fashion, proteins that have to bind to positively charged molecules have surfaces rich with negatively charged amino acids like

glutamate

and

aspartate

, while proteins binding to negatively charged molecules have surfaces rich with positively charged chains like

lysine

and

arginine

. For example, lysine and arginine are highly enriched in

low complexity regions

of nucleic-acid binding proteins.

[50]

There are various

hydrophobicity scales

of amino acid residues.

[121]

Some amino acids have special properties such as

cysteine

, that can form covalent

disulfide bonds

to other cysteine residues,

proline

that forms

a cycle

to the polypeptide backbone, and

glycine

that is more flexible than other amino acids.

Furthermore, glycine and proline are highly enriched within

low complexity regions

of eukaryotic and prokaryotic proteins, whereas the opposite (under-represented) has been observed for highly reactive, or complex, or hydrophobic amino acids, such as cysteine, phenylalanine, tryptophan, methionine, valine, leucine, isoleucine.

[50]

[122]

[123]

Many proteins undergo a range of

posttranslational modifications

, whereby additional chemical groups are attached to the amino acid side chains. Some modifications can produce hydrophobic

lipoproteins

,

[124]

or hydrophilic

glycoproteins

.

[125]

These type of modification allow the reversible targeting of a protein to a membrane. For example, the addition and removal of the fatty acid

palmitic acid

to cysteine residues in some signaling proteins causes the proteins to attach and then detach from cell membranes.

[126]

Table of standard amino acid abbreviations and properties[

edit

]

Amino acid Letter code Side chain

Hydropathy
index

[127]

Molar absorptivity

[128]

Molecular mass

Abundance in proteins (%)

[129]

Standard genetic coding,

IUPAC notation

3 1 Class Polarity

[130]

Charge, at pH 7.4

[130]

Wavelength, λmax (nm) Coefficient, ε (mM−1·cm−1)

Alanine

Ala A Aliphatic Nonpolar Neutral 1.8 89.094 8.76 GCN

Arginine

Arg R Basic Basic polar Positive −4.5 174.203 5.78 MGR, CGY (coding codons can also be expressed by: CGN, AGR)

Asparagine

Asn N Amide Polar Neutral −3.5 132.119 3.93 AAY

Aspartic acid

Asp D Acid Acidic polar Negative −3.5 133.104 5.49 GAY

Cysteine

Cys C Sulfuric Nonpolar Neutral 2.5 250 0.3 121.154 1.38 UGY

Glutamine

Gln Q Amide Polar Neutral −3.5 146.146 3.9 CAR

Glutamic acid

Glu E Acid Acidic polar Negative −3.5 147.131 6.32 GAR

Glycine

Gly G Aliphatic Nonpolar Neutral −0.4 75.067 7.03 GGN

Histidine

His H Basic aromatic Basic polar Positive, 10%
Neutral, 90%
−3.2 211 5.9 155.156 2.26 CAY

Isoleucine

Ile I Aliphatic Nonpolar Neutral 4.5 131.175 5.49 AUH

Leucine

Leu L Aliphatic Nonpolar Neutral 3.8 131.175 9.68 YUR, CUY (coding codons can also be expressed by: CUN, UUR)

Lysine

Lys K Basic Basic polar Positive −3.9 146.189 5.19 AAR

Methionine

Met M Sulfuric Nonpolar Neutral 1.9 149.208 2.32 AUG

Phenylalanine

Phe F Aromatic Nonpolar Neutral 2.8 257, 206, 188 0.2, 9.3, 60.0 165.192 3.87 UUY

Proline

Pro P Cyclic Nonpolar Neutral −1.6 115.132 5.02 CCN

Serine

Ser S Hydroxylic Polar Neutral −0.8 105.093 7.14 UCN, AGY

Threonine

Thr T Hydroxylic Polar Neutral −0.7 119.119 5.53 ACN

Tryptophan

Trp W Aromatic Nonpolar Neutral −0.9 280, 219 5.6, 47.0 204.228 1.25 UGG

Tyrosine

Tyr Y Aromatic Polar Neutral −1.3 274, 222, 193 1.4, 8.0, 48.0 181.191 2.91 UAY

Valine

Val V Aliphatic Nonpolar Neutral 4.2 117.148 6.73 GUN

Two additional amino acids are in some species coded for by

codons

that are usually interpreted as

stop codons

:

21st and 22nd amino acids 3-letter 1-letter

Molecular mass

Selenocysteine

Sec U 168.064

Pyrrolysine

Pyl O 255.313

In addition to the specific amino acid codes, placeholders are used in cases where

chemical

or

crystallographic

analysis of a peptide or protein cannot conclusively determine the identity of a residue. They are also used to summarise

conserved protein sequence

motifs. The use of single letters to indicate sets of similar residues is similar to the use of

abbreviation codes for degenerate bases

.

[131]

[132]

Ambiguous amino acids 3-letter 1-letter Amino acids included Codons included
Any / unknown Xaa X All NNN

Asparagine

or aspartic acid

Asx B D, N RAY

Glutamine

or glutamic acid

Glx Z E, Q SAR

Leucine

or isoleucine

Xle J I, L YTR, ATH, CTY (coding codons can also be expressed by: CTN, ATH, TTR; MTY, YTR, ATA; MTY, HTA, YTG)

Hydrophobic

Φ V, I, L, F, W, Y, M NTN, TAY, TGG

Aromatic

Ω F, W, Y, H YWY, TTY, TGG (coding codons can also be expressed by: TWY, CAY, TGG)

Aliphatic

(non-aromatic)

Ψ V, I, L, M VTN, TTR (coding codons can also be expressed by: NTR, VTY)
Small π P, G, A, S BCN, RGY, GGR

Hydrophilic

ζ S, T, H, N, Q, E, D, K, R VAN, WCN, CGN, AGY (coding codons can also be expressed by: VAN, WCN, MGY, CGP)

Positively-charged

+ K, R, H ARR, CRY, CGR

Negatively-charged

D, E GAN

Unk is sometimes used instead of Xaa, but is less standard.

In addition, many

nonstandard amino acids

have a specific code. For example, several peptide drugs, such as

Bortezomib

and

MG132

, are

artificially synthesized

and retain their

protecting groups

, which have specific codes. Bortezomib is

Pyz

–Phe–boroLeu, and MG132 is

Z

–Leu–Leu–Leu–al. To aid in the analysis of protein structure,

photo-reactive amino acid analogs

are available. These include

photoleucine

(pLeu) and

photomethionine

(pMet).

[133]

Chemical analysis[

edit

]

The total nitrogen content of organic matter is mainly formed by the amino groups in proteins. The Total Kjeldahl Nitrogen (

TKN

) is a measure of nitrogen widely used in the analysis of (waste) water, soil, food, feed and organic matter in general. As the name suggests, the

Kjeldahl method

is applied. More sensitive methods are available.

[134]

[135]

See also[

edit

]

  • Amino acid dating

  • Beta-peptide

  • Degron

  • Erepsin

  • Homochirality

  • Hyperaminoacidemia

  • Leucines

  • Miller–Urey experiment

  • Nucleic acid sequence

  • RNA codon table

Notes[

edit

]

  1. ^

    Proline

    is an exception to this general formula. It lacks the NH2 group because of the

    cyclization

    of the side chain and is known as an

    imino acid

    ; it falls under the category of special structured amino acids.

  2. ^

    For example,

    ruminants

    such as cows obtain a number of amino acids via

    microbes

    in the

    first two stomach chambers

    .

References[

edit

]

  1. ^

    Nelson DL, Cox MM (2005). Principles of Biochemistry (4th ed.). New York: W. H. Freeman.

    ISBN

     

    0-7167-4339-6

    .

  2. ^

    “amino acid”

    . Cambridge Dictionaries Online. Cambridge University Press. 2015. Retrieved 3 July 2015.

  3. ^

    Wagner I, Musso H (November 1983). “New Naturally Occurring Amino Acids”.

    Angewandte Chemie International Edition in English

    . 22 (11): 816–828.

    doi

    :

    10.1002/anie.198308161

    .

    closed access

  4. ^

    Latham MC (1997).

    “Chapter 8. Body composition, the functions of food, metabolism and energy”

    . Human nutrition in the developing world. Food and Nutrition Series – No. 29. Rome: Food and Agriculture Organization of the United Nations.

  5. ^

    Clark, Jim (August 2007).

    “An introduction to amino acids”

    . chemguide. Retrieved 4 July 2015.

  6. ^

    Jakubke H, Sewald N (2008).

    “Amino acids”

    . Peptides from A to Z: A Concise Encyclopedia. Germany: Wiley-VCH. p. 20.

    ISBN

     

    9783527621170

    – via Google Books.

  7. ^

    Pollegioni L, Servi S, eds. (2012). Unnatural Amino Acids: Methods and Protocols. Methods in Molecular Biology. 794. Humana Press. p. v.

    doi

    :

    10.1007/978-1-61779-331-8

    .

    ISBN

     

    978-1-61779-331-8

    .

    OCLC

     

    756512314

    .

    S2CID

     

    3705304

    .

  8. ^

    Hertweck C (October 2011). “Biosynthesis and Charging of Pyrrolysine, the 22nd Genetically Encoded Amino Acid”.

    Angewandte Chemie International Edition

    . 50 (41): 9540–9541.

    doi

    :

    10.1002/anie.201103769

    .

    PMID

     

    21796749

    .

    closed access

  9. ^

    “Chapter 1: Proteins are the Body’s Worker Molecules”

    . The Structures of Life. National Institute of General Medical Sciences. 27 October 2011. Retrieved 20 May 2008.

  10. ^

    Michal G, Schomburg D, eds. (2012). Biochemical Pathways: An Atlas of Biochemistry and Molecular Biology (2nd ed.). Oxford: Wiley-Blackwell. p. 5.

    ISBN

     

    978-0-470-14684-2

    .

  11. ^

    a

    b

    Tjong H (2008).

    Modeling Electrostatic Contributions to Protein Folding and Binding

    (PhD thesis). Florida State University. p. 1 footnote.

  12. ^

    a

    b

    Stewart L, Burgin AB (2005). Atta-Ur-Rahman, Springer BA, Caldwell GW (eds.).

    “Whole Gene Synthesis: A Gene-O-Matic Future”

    . Frontiers in Drug Design and Discovery.

    Bentham Science Publishers

    . 1: 299.

    doi

    :

    10.2174/1574088054583318

    .

    ISBN

     

    978-1-60805-199-1

    .

    ISSN

     

    1574-0889

    .

  13. ^

    a

    b

    Elzanowski A, Ostell J (7 April 2008).

    “The Genetic Codes”

    . National Center for Biotechnology Information (NCBI). Retrieved 10 March 2010.

  14. ^

    a

    b

    Xie J, Schultz PG (December 2005). “Adding amino acids to the genetic repertoire”. Current Opinion in Chemical Biology. 9 (6): 548–554.

    doi

    :

    10.1016/j.cbpa.2005.10.011

    .

    PMID

     

    16260173

    .

  15. ^

    a

    b

    Wang Q, Parrish AR, Wang L (March 2009).

    “Expanding the genetic code for biological studies”

    . Chemistry & Biology. 16 (3): 323–336.

    doi

    :

    10.1016/j.chembiol.2009.03.001

    .

    PMC

     

    2696486

    .

    PMID

     

    19318213

    .

  16. ^

    Simon M (2005).

    Emergent computation: emphasizing bioinformatics

    . New York: AIP Press/Springer Science+Business Media. pp. 

    105–106

    .

    ISBN

     

    978-0-387-22046-8

    .

  17. ^

    Petroff OA (December 2002). “GABA and glutamate in the human brain”. The Neuroscientist. 8 (6): 562–573.

    doi

    :

    10.1177/1073858402238515

    .

    PMID

     

    12467378

    .

    S2CID

     

    84891972

    .

  18. ^

    Vickery HB, Schmidt CL (1931). “The history of the discovery of the amino acids”. Chem. Rev. 9 (2): 169–318.

    doi

    :

    10.1021/cr60033a001

    .

  19. ^

    Hansen S (May 2015).

    “Die Entdeckung der proteinogenen Aminosäuren von 1805 in Paris bis 1935 in Illinois”

    (PDF) (in German). Berlin. Archived from

    the original

    (PDF) on 1 December 2017.

  20. ^

    Vauquelin LN, Robiquet PJ (1806). “The discovery of a new plant principle in Asparagus sativus”. Annales de Chimie. 57: 88–93.

  21. ^

    a

    b

    Anfinsen CB, Edsall JT, Richards FM (1972).

    Advances in Protein Chemistry

    . New York: Academic Press. pp. 

    99, 103

    .

    ISBN

     

    978-0-12-034226-6

    .

  22. ^

    Wollaston WH (1810). “On cystic oxide, a new species of urinary calculus”. Philosophical Transactions of the Royal Society. 100: 223–230.

    doi

    :

    10.1098/rstl.1810.0015

    .

    S2CID

     

    110151163

    .

  23. ^

    Baumann E (1884).

    “Über cystin und cystein”

    . Z Physiol Chem. 8 (4): 299–305. Archived from

    the original

    on 14 March 2011. Retrieved 28 March 2011.

  24. ^

    Braconnot HM (1820). “Sur la conversion des matières animales en nouvelles substances par le moyen de l’acide sulfurique”. Annales de Chimie et de Physique. 2nd Series. 13: 113–125.

  25. ^

    Simoni RD, Hill RL, Vaughan M (September 2002).

    “The discovery of the amino acid threonine: the work of William C. Rose [classical article]”

    . The Journal of Biological Chemistry. 277 (37): E25.

    doi

    :

    10.1016/S0021-9258(20)74369-3

    .

    PMID

     

    12218068

    .

  26. ^

    McCoy RH, Meyer CE, Rose WC (1935).

    “Feeding Experiments with Mixtures of Highly Purified Amino Acids. VIII. Isolation and Identification of a New Essential Amino Acid”

    . Journal of Biological Chemistry. 112: 283–302.

    doi

    :

    10.1016/S0021-9258(18)74986-7

    .

  27. ^

    Menten, P. Dictionnaire de chimie: Une approche étymologique et historique. De Boeck, Bruxelles.

    link

    .

  28. ^

    Harper D.

    “amino-“

    . Online Etymology Dictionary. Retrieved 19 July 2010.

  29. ^

    Paal C (1894).

    “Ueber die Einwirkung von Phenyl‐i‐cyanat auf organische Aminosäuren”

    . Berichte der Deutschen Chemischen Gesellschaft. 27: 974–979.

    doi

    :

    10.1002/cber.189402701205

    . Archived from

    the original

    on 25 July 2020.

  30. ^

    Fruton JS (1990). “Chapter 5- Emil Fischer and Franz Hofmeister”. Contrasts in Scientific Style: Research Groups in the Chemical and Biochemical Sciences. 191. American Philosophical Society. pp. 163–165.

    ISBN

     

    978-0-87169-191-0

    .

  31. ^

    “Alpha amino acid”

    . The Merriam-Webster.com Medical Dictionary. Merriam-Webster Inc.

  32. ^

    Proline

    at the US National Library of Medicine

    Medical Subject Headings

    (MeSH)

  33. ^

    Matts RL (2005).

    “Amino acids”

    . Biochemistry 5753: Principles of Biochemistry. Archived from

    the original

    on 18 January 2008. Retrieved 3 January 2015.

  34. ^

    IUPAC

    ,

    Compendium of Chemical Terminology

    , 2nd ed. (the “Gold Book”) (1997). Online corrected version:  (2006–) “

    Imino acids

    “.

    doi

    :

    10.1351/goldbook.I02959

  35. ^

    a

    b

    c

    d

    e

    f

    Creighton TH (1993).

    “Chapter 1”

    . Proteins: structures and molecular properties. San Francisco: W. H. Freeman.

    ISBN

     

    978-0-7167-7030-5

    .

  36. ^

    Hatem SM (2006).

    “Gas chromatographic determination of Amino Acid Enantiomers in tobacco and bottled wines”

    . University of Giessen. Archived from

    the original

    on 22 January 2009. Retrieved 17 November 2008.

  37. ^

    “Nomenclature and Symbolism for Amino Acids and Peptides”

    . IUPAC-IUB Joint Commission on Biochemical Nomenclature. 1983. Archived from

    the original

    on 9 October 2008. Retrieved 17 November 2008.

  38. ^

    Jodidi SL (1 March 1926). “The Formol Titration of Certain Amino Acids”. Journal of the American Chemical Society. 48 (3): 751–753.

    doi

    :

    10.1021/ja01414a033

    .

  39. ^

    Liebecq C, ed. (1992). Biochemical Nomenclature and Related Documents (2nd ed.). Portland Press. pp. 39–69.

    ISBN

     

    978-1-85578-005-7

    .

  40. ^

    Smith AD (1997). Oxford Dictionary of Biochemistry and Molecular Biology. Oxford: Oxford University Press. p. 535.

    ISBN

     

    978-0-19-854768-6

    .

    OCLC

     

    37616711

    .

  41. ^

    Simmons WJ, Meisenberg G (2006).

    Principles of medical biochemistry

    . Mosby Elsevier. p. 

    19

    .

    ISBN

     

    978-0-323-02942-1

    .

  42. ^

    Fennema OR (19 June 1996). Food Chemistry 3rd Ed. CRC Press. pp. 327–328.

    ISBN

     

    978-0-8247-9691-4

    .

  43. ^

    Rodnina MV, Beringer M, Wintermeyer W (January 2007). “How ribosomes make peptide bonds”. Trends in Biochemical Sciences. 32 (1): 20–26.

    doi

    :

    10.1016/j.tibs.2006.11.007

    .

    PMID

     

    17157507

    .

  44. ^

    Driscoll DM, Copeland PR (2003). “Mechanism and regulation of selenoprotein synthesis”. Annual Review of Nutrition. 23 (1): 17–40.

    doi

    :

    10.1146/annurev.nutr.23.011702.073318

    .

    PMID

     

    12524431

    .

  45. ^

    Krzycki JA (December 2005). “The direct genetic encoding of pyrrolysine”. Current Opinion in Microbiology. 8 (6): 706–712.

    doi

    :

    10.1016/j.mib.2005.10.009

    .

    PMID

     

    16256420

    .

  46. ^

    Théobald-Dietrich A, Giegé R, Rudinger-Thirion J (2005). “Evidence for the existence in mRNAs of a hairpin element responsible for ribosome dependent pyrrolysine insertion into proteins”. Biochimie. 87 (9–10): 813–817.

    doi

    :

    10.1016/j.biochi.2005.03.006

    .

    PMID

     

    16164991

    .

  47. ^

    Trifonov EN (December 2000). “Consensus temporal order of amino acids and evolution of the triplet code”. Gene. 261 (1): 139–151.

    doi

    :

    10.1016/S0378-1119(00)00476-5

    .

    PMID

     

    11164045

    .

  48. ^

    Higgs PG, Pudritz RE (June 2009). “A thermodynamic basis for prebiotic amino acid synthesis and the nature of the first genetic code”. Astrobiology. 9 (5): 483–90.

    arXiv

    :

    0904.0402

    .

    Bibcode

    :

    2009AsBio…9..483H

    .

    doi

    :

    10.1089/ast.2008.0280

    .

    PMID

     

    19566427

    .

    S2CID

     

    9039622

    .

  49. ^

    Chaliotis A, Vlastaridis P, Mossialos D, Ibba M, Becker HD, Stathopoulos C, Amoutzias GD (February 2017).

    “The complex evolutionary history of aminoacyl-tRNA synthetases”

    . Nucleic Acids Research. 45 (3): 1059–1068.

    doi

    :

    10.1093/nar/gkw1182

    .

    PMC

     

    5388404

    .

    PMID

     

    28180287

    .

  50. ^

    a

    b

    c

    Ntountoumi C, Vlastaridis P, Mossialos D, Stathopoulos C, Iliopoulos I, Promponas V, et al. (November 2019).

    “Low complexity regions in the proteins of prokaryotes perform important functional roles and are highly conserved”

    . Nucleic Acids Research. 47 (19): 9998–10009.

    doi

    :

    10.1093/nar/gkz730

    .

    PMC

     

    6821194

    .

    PMID

     

    31504783

    .

  51. ^

    Vermeer C (March 1990).

    “Gamma-carboxyglutamate-containing proteins and the vitamin K-dependent carboxylase”

    . The Biochemical Journal. 266 (3): 625–636.

    doi

    :

    10.1042/bj2660625

    .

    PMC

     

    1131186

    .

    PMID

     

    2183788

    .

  52. ^

    Bhattacharjee A, Bansal M (March 2005). “Collagen structure: the Madras triple helix and the current scenario”. IUBMB Life. 57 (3): 161–172.

    doi

    :

    10.1080/15216540500090710

    .

    PMID

     

    16036578

    .

    S2CID

     

    7211864

    .

  53. ^

    Park MH (February 2006).

    “The post-translational synthesis of a polyamine-derived amino acid, hypusine, in the eukaryotic translation initiation factor 5A (eIF5A)”

    . Journal of Biochemistry. 139 (2): 161–169.

    doi

    :

    10.1093/jb/mvj034

    .

    PMC

     

    2494880

    .

    PMID

     

    16452303

    .

  54. ^

    Blenis J, Resh MD (December 1993). “Subcellular localization specified by protein acylation and phosphorylation”. Current Opinion in Cell Biology. 5 (6): 984–989.

    doi

    :

    10.1016/0955-0674(93)90081-Z

    .

    PMID

     

    8129952

    .

  55. ^

    Curis E, Nicolis I, Moinard C, Osowska S, Zerrouk N, Bénazeth S, Cynober L (November 2005). “Almost all about citrulline in mammals”. Amino Acids. 29 (3): 177–205.

    doi

    :

    10.1007/s00726-005-0235-4

    .

    PMID

     

    16082501

    .

    S2CID

     

    23877884

    .

  56. ^

    Coxon KM, Chakauya E, Ottenhof HH, Whitney HM, Blundell TL, Abell C, Smith AG (August 2005). “Pantothenate biosynthesis in higher plants”. Biochemical Society Transactions. 33 (Pt 4): 743–746.

    doi

    :

    10.1042/BST0330743

    .

    PMID

     

    16042590

    .

  57. ^

    Kryukov GV, Castellano S, Novoselov SV, Lobanov AV, Zehtab O, Guigó R, Gladyshev VN (May 2003).

    “Characterization of mammalian selenoproteomes”

    . Science. 300 (5624): 1439–1443.

    Bibcode

    :

    2003Sci…300.1439K

    .

    doi

    :

    10.1126/science.1083516

    .

    PMID

     

    12775843

    .

    S2CID

     

    10363908

    .

  58. ^

    Gromer S, Urig S, Becker K (January 2004). “The thioredoxin system—from science to clinic”. Medicinal Research Reviews. 24 (1): 40–89.

    doi

    :

    10.1002/med.10051

    .

    PMID

     

    14595672

    .

    S2CID

     

    1944741

    .

  59. ^

    Sakami W, Harrington H (1963). “Amino acid metabolism”. Annual Review of Biochemistry. 32 (1): 355–398.

    doi

    :

    10.1146/annurev.bi.32.070163.002035

    .

    PMID

     

    14144484

    .

  60. ^

    Brosnan JT (April 2000).

    “Glutamate, at the interface between amino acid and carbohydrate metabolism”

    . The Journal of Nutrition. 130 (4S Suppl): 988S–990S.

    doi

    :

    10.1093/jn/130.4.988S

    .

    PMID

     

    10736367

    .

  61. ^

    Young VR, Ajami AM (September 2001).

    “Glutamine: the emperor or his clothes?”

    . The Journal of Nutrition. 131 (9 Suppl): 2449S–2459S, 2486S–2487S.

    doi

    :

    10.1093/jn/131.9.2449S

    .

    PMID

     

    11533293

    .

  62. ^

    Young VR (August 1994). “Adult amino acid requirements: the case for a major revision in current recommendations”. The Journal of Nutrition. 124 (8 Suppl): 1517S–1523S.

    doi

    :

    10.1093/jn/124.suppl_8.1517S

    .

    PMID

     

    8064412

    .

  63. ^

    Fürst P, Stehle P (June 2004).

    “What are the essential elements needed for the determination of amino acid requirements in humans?”

    . The Journal of Nutrition. 134 (6 Suppl): 1558S–1565S.

    doi

    :

    10.1093/jn/134.6.1558S

    .

    PMID

     

    15173430

    .

  64. ^

    Reeds PJ (July 2000).

    “Dispensable and indispensable amino acids for humans”

    . The Journal of Nutrition. 130 (7): 1835S–1840S.

    doi

    :

    10.1093/jn/130.7.1835S

    .

    PMID

     

    10867060

    .

  65. ^

    Imura K, Okada A (January 1998). “Amino acid metabolism in pediatric patients”. Nutrition. 14 (1): 143–148.

    doi

    :

    10.1016/S0899-9007(97)00230-X

    .

    PMID

     

    9437700

    .

  66. ^

    Lourenço R, Camilo ME (2002). “Taurine: a conditionally essential amino acid in humans? An overview in health and disease”. Nutricion Hospitalaria. 17 (6): 262–270.

    PMID

     

    12514918

    .

  67. ^

    Holtcamp W (March 2012).

    “The emerging science of BMAA: do cyanobacteria contribute to neurodegenerative disease?”

    . Environmental Health Perspectives. 120 (3): A110–A116.

    doi

    :

    10.1289/ehp.120-a110

    .

    PMC

     

    3295368

    .

    PMID

     

    22382274

    .

  68. ^

    Cox PA, Davis DA, Mash DC, Metcalf JS, Banack SA (January 2016).

    “Dietary exposure to an environmental toxin triggers neurofibrillary tangles and amyloid deposits in the brain”

    . Proceedings: Biological Sciences. 283 (1823): 20152397.

    doi

    :

    10.1098/rspb.2015.2397

    .

    PMC

     

    4795023

    .

    PMID

     

    26791617

    .

  69. ^

    a

    b

    Brook MS, Wilkinson DJ, Phillips BE, Perez-Schindler J, Philp A, Smith K, Atherton PJ (January 2016).

    “Skeletal muscle homeostasis and plasticity in youth and ageing: impact of nutrition and exercise”

    . Acta Physiologica. 216 (1): 15–41.

    doi

    :

    10.1111/apha.12532

    .

    PMC

     

    4843955

    .

    PMID

     

    26010896

    .

  70. ^

    Lipton JO, Sahin M (October 2014).

    “The neurology of mTOR”

    . Neuron. 84 (2): 275–291.

    doi

    :

    10.1016/j.neuron.2014.09.034

    .

    PMC

     

    4223653

    .

    PMID

     

    25374355

    .

    Figure 2: The mTOR Signaling Pathway

  71. ^

    a

    b

    Phillips SM (May 2014).

    “A brief review of critical processes in exercise-induced muscular hypertrophy”

    . Sports Medicine. 44 (Suppl. 1): S71–S77.

    doi

    :

    10.1007/s40279-014-0152-3

    .

    PMC

     

    4008813

    .

    PMID

     

    24791918

    .

  72. ^

    Broadley KJ (March 2010). “The vascular effects of trace amines and amphetamines”. Pharmacology & Therapeutics. 125 (3): 363–375.

    doi

    :

    10.1016/j.pharmthera.2009.11.005

    .

    PMID

     

    19948186

    .

  73. ^

    Lindemann L, Hoener MC (May 2005). “A renaissance in trace amines inspired by a novel GPCR family”. Trends in Pharmacological Sciences. 26 (5): 274–281.

    doi

    :

    10.1016/j.tips.2005.03.007

    .

    PMID

     

    15860375

    .

  74. ^

    Wang X, Li J, Dong G, Yue J (February 2014). “The endogenous substrates of brain CYP2D”. European Journal of Pharmacology. 724: 211–218.

    doi

    :

    10.1016/j.ejphar.2013.12.025

    .

    PMID

     

    24374199

    .

  75. ^

    Savelieva KV, Zhao S, Pogorelov VM, Rajan I, Yang Q, Cullinan E, Lanthorn TH (2008). Bartolomucci A (ed.).

    “Genetic disruption of both tryptophan hydroxylase genes dramatically reduces serotonin and affects behavior in models sensitive to antidepressants”

    . PLOS ONE. 3 (10): e3301.

    Bibcode

    :

    2008PLoSO…3.3301S

    .

    doi

    :

    10.1371/journal.pone.0003301

    .

    PMC

     

    2565062

    .

    PMID

     

    18923670

    .

  76. ^

    Shemin D, Rittenberg D (December 1946).

    “The biological utilization of glycine for the synthesis of the protoporphyrin of hemoglobin”

    . The Journal of Biological Chemistry. 166 (2): 621–625.

    doi

    :

    10.1016/S0021-9258(17)35200-6

    .

    PMID

     

    20276176

    .

  77. ^

    Tejero J, Biswas A, Wang ZQ, Page RC, Haque MM, Hemann C, Zweier JL, Misra S, Stuehr DJ (November 2008).

    “Stabilization and characterization of a heme-oxy reaction intermediate in inducible nitric-oxide synthase”

    . The Journal of Biological Chemistry. 283 (48): 33498–33507.

    doi

    :

    10.1074/jbc.M806122200

    .

    PMC

     

    2586280

    .

    PMID

     

    18815130

    .

  78. ^

    Rodríguez-Caso C, Montañez R, Cascante M, Sánchez-Jiménez F, Medina MA (August 2006).

    “Mathematical modeling of polyamine metabolism in mammals”

    . The Journal of Biological Chemistry. 281 (31): 21799–21812.

    doi

    :

    10.1074/jbc.M602756200

    .

    PMID

     

    16709566

    .

  79. ^

    a

    b

    Stryer L, Berg JM, Tymoczko JL (2002).

    Biochemistry

    (5th ed.). New York: W.H. Freeman. pp. 

    693–698

    .

    ISBN

     

    978-0-7167-4684-3

    .

  80. ^

    Hylin JW (1969). “Toxic peptides and amino acids in foods and feeds”. Journal of Agricultural and Food Chemistry. 17 (3): 492–496.

    doi

    :

    10.1021/jf60163a003

    .

  81. ^

    Turner BL, Harborne JB (1967). “Distribution of canavanine in the plant kingdom”. Phytochemistry. 6 (6): 863–866.

    doi

    :

    10.1016/S0031-9422(00)86033-1

    .

  82. ^

    Ekanayake S, Skog K, Asp NG (May 2007). “Canavanine content in sword beans (Canavalia gladiata): analysis and effect of processing”. Food and Chemical Toxicology. 45 (5): 797–803.

    doi

    :

    10.1016/j.fct.2006.10.030

    .

    PMID

     

    17187914

    .

  83. ^

    Rosenthal GA (2001). “L-Canavanine: a higher plant insecticidal allelochemical”. Amino Acids. 21 (3): 319–330.

    doi

    :

    10.1007/s007260170017

    .

    PMID

     

    11764412

    .

    S2CID

     

    3144019

    .

  84. ^

    Hammond AC (May 1995).

    “Leucaena toxicosis and its control in ruminants”

    . Journal of Animal Science. 73 (5): 1487–1492.

    doi

    :

    10.2527/1995.7351487x

    .

    PMID

     

    7665380

    .[

    permanent dead link

    ]

  85. ^

    a

    b

    Leuchtenberger W, Huthmacher K, Drauz K (November 2005). “Biotechnological production of amino acids and derivatives: current status and prospects”. Applied Microbiology and Biotechnology. 69 (1): 1–8.

    doi

    :

    10.1007/s00253-005-0155-y

    .

    PMID

     

    16195792

    .

    S2CID

     

    24161808

    .

  86. ^

    Ashmead HD (1993). The Role of Amino Acid Chelates in Animal Nutrition. Westwood: Noyes Publications.

  87. ^

    Garattini S (April 2000).

    “Glutamic acid, twenty years later”

    . The Journal of Nutrition. 130 (4S Suppl): 901S–909S.

    doi

    :

    10.1093/jn/130.4.901S

    .

    PMID

     

    10736350

    .

  88. ^

    Stegink LD (July 1987). “The aspartame story: a model for the clinical testing of a food additive”. The American Journal of Clinical Nutrition. 46 (1 Suppl): 204–215.

    doi

    :

    10.1093/ajcn/46.1.204

    .

    PMID

     

    3300262

    .

  89. ^

    Albion Laboratories, Inc.

    “Albion Ferrochel Website”

    . Retrieved 12 July 2011.

  90. ^

    Ashmead HD (1986). Foliar Feeding of Plants with Amino Acid Chelates. Park Ridge: Noyes Publications.

  91. ^

    Turner EH, Loftis JM, Blackwell AD (March 2006).

    “Serotonin a la carte: supplementation with the serotonin precursor 5-hydroxytryptophan”

    . Pharmacology & Therapeutics. 109 (3): 325–338.

    doi

    :

    10.1016/j.pharmthera.2005.06.004

    .

    PMID

     

    16023217

    .

  92. ^

    Kostrzewa RM, Nowak P, Kostrzewa JP, Kostrzewa RA, Brus R (March 2005). “Peculiarities of L-DOPA treatment of Parkinson’s disease”. Amino Acids. 28 (2): 157–164.

    doi

    :

    10.1007/s00726-005-0162-4

    .

    PMID

     

    15750845

    .

    S2CID

     

    33603501

    .

  93. ^

    Heby O, Persson L, Rentala M (August 2007). “Targeting the polyamine biosynthetic enzymes: a promising approach to therapy of African sleeping sickness, Chagas’ disease, and leishmaniasis”. Amino Acids. 33 (2): 359–366.

    doi

    :

    10.1007/s00726-007-0537-9

    .

    PMID

     

    17610127

    .

    S2CID

     

    26273053

    .

  94. ^

    Cruz-Vera LR, Magos-Castro MA, Zamora-Romo E, Guarneros G (2004).

    “Ribosome stalling and peptidyl-tRNA drop-off during translational delay at AGA codons”

    . Nucleic Acids Research. 32 (15): 4462–4468.

    doi

    :

    10.1093/nar/gkh784

    .

    PMC

     

    516057

    .

    PMID

     

    15317870

    .

  95. ^

    Andy C (October 2012).

    “Molecules ‘too dangerous for nature’ kill cancer cells”

    . New Scientist.

  96. ^

    “Lethal DNA tags could keep innocent people out of jail”

    . New Scientist. 2 May 2013.

  97. ^

    Hanessian S (1993). “Reflections on the total synthesis of natural products: Art, craft, logic, and the chiron approach”. Pure and Applied Chemistry. 65 (6): 1189–1204.

    doi

    :

    10.1351/pac199365061189

    .

    S2CID

     

    43992655

    .

  98. ^

    Blaser HU (1992). “The chiral pool as a source of enantioselective catalysts and auxiliaries”. Chemical Reviews. 92 (5): 935–952.

    doi

    :

    10.1021/cr00013a009

    .

  99. ^

    Sanda F, Endo T (1999). “Syntheses and functions of polymers based on amino acids”. Macromolecular Chemistry and Physics. 200 (12): 2651–2661.

    doi

    :

    10.1002/(SICI)1521-3935(19991201)200:12<2651::AID-MACP2651>3.0.CO;2-P

    .

  100. ^

    Gross RA, Kalra B (August 2002).

    “Biodegradable polymers for the environment”

    . Science. 297 (5582): 803–807.

    Bibcode

    :

    2002Sci…297..803G

    .

    doi

    :

    10.1126/science.297.5582.803

    .

    PMID

     

    12161646

    .

  101. ^

    Low KC, Wheeler AP, Koskan LP (1996). Commercial poly(aspartic acid) and Its Uses. Advances in Chemistry Series. 248. Washington, D.C.:

    American Chemical Society

    .

  102. ^

    Thombre SM, Sarwade BD (2005). “Synthesis and Biodegradability of Polyaspartic Acid: A Critical Review”. Journal of Macromolecular Science, Part A. 42 (9): 1299–1315.

    doi

    :

    10.1080/10601320500189604

    .

    S2CID

     

    94818855

    .

  103. ^

    Bourke SL, Kohn J (April 2003). “Polymers derived from the amino acid L-tyrosine: polycarbonates, polyarylates and copolymers with poly(ethylene glycol)”. Advanced Drug Delivery Reviews. 55 (4): 447–466.

    doi

    :

    10.1016/S0169-409X(03)00038-3

    .

    PMID

     

    12706045

    .

  104. ^

    Drauz K, Grayson I, Kleemann A, Krimmer H, Leuchtenberger W, Weckbecker C (2006).

    Ullmann’s Encyclopedia of Industrial Chemistry

    . Weinheim: Wiley-VCH.

    doi

    :

    10.1002/14356007.a02_057.pub2

    .

  105. ^

    Jones RC, Buchanan BB, Gruissem W (2000).

    Biochemistry & molecular biology of plants

    . Rockville, Md: American Society of Plant Physiologists. pp. 

    371–372

    .

    ISBN

     

    978-0-943088-39-6

    .

  106. ^

    Brosnan JT, Brosnan ME (June 2006).

    “The sulfur-containing amino acids: an overview”

    . The Journal of Nutrition. 136 (6 Suppl): 1636S–1640S.

    doi

    :

    10.1093/jn/136.6.1636S

    .

    PMID

     

    16702333

    .

  107. ^

    Kivirikko KI, Pihlajaniemi T (1998). “Collagen hydroxylases and the protein disulfide isomerase subunit of prolyl 4-hydroxylases”. Advances in Enzymology and Related Areas of Molecular Biology. Advances in Enzymology – and Related Areas of Molecular Biology. 72. pp. 325–398.

    doi

    :

    10.1002/9780470123188.ch9

    .

    ISBN

     

    9780470123188

    .

    PMID

     

    9559057

    .

  108. ^

    Whitmore L, Wallace BA (May 2004). “Analysis of peptaibol sequence composition: implications for in vivo synthesis and channel formation”. European Biophysics Journal. 33 (3): 233–237.

    doi

    :

    10.1007/s00249-003-0348-1

    .

    PMID

     

    14534753

    .

    S2CID

     

    24638475

    .

  109. ^

    Alexander L, Grierson D (October 2002).

    “Ethylene biosynthesis and action in tomato: a model for climacteric fruit ripening”

    . Journal of Experimental Botany. 53 (377): 2039–2055.

    doi

    :

    10.1093/jxb/erf072

    .

    PMID

     

    12324528

    .

  110. ^

    Elmore DT, Barrett GC (1998).

    Amino acids and peptides

    . Cambridge, UK: Cambridge University Press. pp. 

    48

    –60.

    ISBN

     

    978-0-521-46827-5

    .

  111. ^

    Gutteridge A, Thornton JM (November 2005). “Understanding nature’s catalytic toolkit”. Trends in Biochemical Sciences. 30 (11): 622–629.

    doi

    :

    10.1016/j.tibs.2005.09.006

    .

    PMID

     

    16214343

    .

  112. ^

    Ibba M, Söll D (May 2001).

    “The renaissance of aminoacyl-tRNA synthesis”

    . EMBO Reports. 2 (5): 382–387.

    doi

    :

    10.1093/embo-reports/kve095

    .

    PMC

     

    1083889

    .

    PMID

     

    11375928

    .

  113. ^

    Lengyel P, Söll D (June 1969).

    “Mechanism of protein biosynthesis”

    . Bacteriological Reviews. 33 (2): 264–301.

    doi

    :

    10.1128/MMBR.33.2.264-301.1969

    .

    PMC

     

    378322

    .

    PMID

     

    4896351

    .

  114. ^

    Wu G, Fang YZ, Yang S, Lupton JR, Turner ND (March 2004).

    “Glutathione metabolism and its implications for health”

    . The Journal of Nutrition. 134 (3): 489–492.

    doi

    :

    10.1093/jn/134.3.489

    .

    PMID

     

    14988435

    .

  115. ^

    Meister A (November 1988).

    “Glutathione metabolism and its selective modification”

    . The Journal of Biological Chemistry. 263 (33): 17205–17208.

    doi

    :

    10.1016/S0021-9258(19)77815-6

    .

    PMID

     

    3053703

    .

  116. ^

    Carpino LA (1992). “1-Hydroxy-7-azabenzotriazole. An efficient peptide coupling additive”. Journal of the American Chemical Society. 115 (10): 4397–4398.

    doi

    :

    10.1021/ja00063a082

    .

  117. ^

    Marasco D, Perretta G, Sabatella M, Ruvo M (October 2008). “Past and future perspectives of synthetic peptide libraries”. Current Protein & Peptide Science. 9 (5): 447–467.

    doi

    :

    10.2174/138920308785915209

    .

    PMID

     

    18855697

    .

  118. ^

    Konara S, Gagnona K, Clearfield A, Thompson C, Hartle J, Ericson C, Nelson C (2010). “Structural determination and characterization of copper and zinc bis-glycinates with X-ray crystallography and mass spectrometry”. Journal of Coordination Chemistry. 63 (19): 3335–3347.

    doi

    :

    10.1080/00958972.2010.514336

    .

    S2CID

     

    94822047

    .

  119. ^

    Stipanuk MH (2006). Biochemical, physiological, & molecular aspects of human nutrition (2nd ed.). Saunders Elsevier.

  120. ^

    Dghaym RD, Dhawan R, Arndtsen BA (September 2001). “The Use of Carbon Monoxide and Imines as Peptide Derivative Synthons: A Facile Palladium-Catalyzed Synthesis of α-Amino Acid Derived Imidazolines”. Angewandte Chemie. 40 (17): 3228–3230.

    doi

    :

    10.1002/(SICI)1521-3773(19980703)37:12<1634::AID-ANIE1634>3.0.CO;2-C

    .

    PMID

     

    29712039

    .

  121. ^

    Urry DW (2004). “The change in Gibbs free energy for hydrophobic association: Derivation and evaluation by means of inverse temperature transitions”. Chemical Physics Letters. 399 (1–3): 177–183.

    Bibcode

    :

    2004CPL…399..177U

    .

    doi

    :

    10.1016/S0009-2614(04)01565-9

    .

  122. ^

    Marcotte EM, Pellegrini M, Yeates TO, Eisenberg D (October 1999). “A census of protein repeats”. Journal of Molecular Biology. 293 (1): 151–60.

    doi

    :

    10.1006/jmbi.1999.3136

    .

    PMID

     

    10512723

    .

  123. ^

    Haerty W, Golding GB (October 2010). Bonen L (ed.). “Low-complexity sequences and single amino acid repeats: not just “junk” peptide sequences”. Genome. 53 (10): 753–62.

    doi

    :

    10.1139/G10-063

    .

    PMID

     

    20962881

    .

  124. ^

    Magee T, Seabra MC (April 2005). “Fatty acylation and prenylation of proteins: what’s hot in fat”. Current Opinion in Cell Biology. 17 (2): 190–196.

    doi

    :

    10.1016/j.ceb.2005.02.003

    .

    PMID

     

    15780596

    .

  125. ^

    Pilobello KT, Mahal LK (June 2007). “Deciphering the glycocode: the complexity and analytical challenge of glycomics”. Current Opinion in Chemical Biology. 11 (3): 300–305.

    doi

    :

    10.1016/j.cbpa.2007.05.002

    .

    PMID

     

    17500024

    .

  126. ^

    Smotrys JE, Linder ME (2004). “Palmitoylation of intracellular signaling proteins: regulation and function”. Annual Review of Biochemistry. 73 (1): 559–587.

    doi

    :

    10.1146/annurev.biochem.73.011303.073954

    .

    PMID

     

    15189153

    .

  127. ^

    Kyte J, Doolittle RF (May 1982). “A simple method for displaying the hydropathic character of a protein”. Journal of Molecular Biology. 157 (1): 105–132.

    CiteSeerX

     

    10.1.1.458.454

    .

    doi

    :

    10.1016/0022-2836(82)90515-0

    .

    PMID

     

    7108955

    .

  128. ^

    Freifelder D (1983). Physical Biochemistry (2nd ed.). W. H. Freeman and Company.

    ISBN

     

    978-0-7167-1315-9

    .[

    page needed

    ]

  129. ^

    Kozlowski LP (January 2017).

    “Proteome-pI: proteome isoelectric point database”

    . Nucleic Acids Research. 45 (D1): D1112–D1116.

    doi

    :

    10.1093/nar/gkw978

    .

    PMC

     

    5210655

    .

    PMID

     

    27789699

    .

  130. ^

    a

    b

    Hausman RE, Cooper GM (2004). The cell: a molecular approach. Washington, D.C: ASM Press. p. 51.

    ISBN

     

    978-0-87893-214-6

    .

  131. ^

    Aasland R, Abrams C, Ampe C, Ball LJ, Bedford MT, Cesareni G, Gimona M, Hurley JH, Jarchau T, Lehto VP, Lemmon MA, Linding R, Mayer BJ, Nagai M, Sudol M, Walter U, Winder SJ (February 2002). “Normalization of nomenclature for peptide motifs as ligands of modular protein domains”. FEBS Letters. 513 (1): 141–144.

    doi

    :

    10.1111/j.1432-1033.1968.tb00350.x

    .

    PMID

     

    11911894

    .

  132. ^

    IUPAC–IUB Commission on Biochemical Nomenclature (1972).

    “A one-letter notation for amino acid sequences”

    . Pure and Applied Chemistry. 31 (4): 641–645.

    doi

    :

    10.1351/pac197231040639

    .

    PMID

     

    5080161

    .

  133. ^

    Suchanek M, Radzikowska A, Thiele C (April 2005).

    “Photo-leucine and photo-methionine allow identification of protein–protein interactions in living cells”

    . Nature Methods. 2 (4): 261–267.

    doi

    :

    10.1038/nmeth752

    .

    PMID

     

    15782218

    .

  134. ^

    Muñoz-Huerta RF, Guevara-Gonzalez RG, Contreras-Medina LM, Torres-Pacheco I, Prado-Olivarez J, Ocampo-Velazquez RV (August 2013).

    “A review of methods for sensing the nitrogen status in plants: advantages, disadvantages and recent advances”

    . Sensors. Basel, Switzerland. 13 (8): 10823–43.

    doi

    :

    10.3390/s130810823

    .

    PMC

     

    3812630

    .

    PMID

     

    23959242

    .

  135. ^

    Martin PD, Malley DF, Manning G, Fuller L (2002). “Determination of soil organic carbon and nitrogen at thefield level using near-infrared spectroscopy”. Canadian Journal of Soil Science. 82 (4): 413–422.

    doi

    :

    10.4141/S01-054

    .

Further reading[

edit

]

  • Tymoczko JL (2012).

    “Protein Composition and Structure”

    .

    Biochemistry

    . New York: W. H. Freeman and company. pp. 28–31.

    ISBN

     

    9781429229364

    .

  • Doolittle RF

    (1989). “Redundancies in protein sequences”. In Fasman GD (ed.). Predictions of Protein Structure and the Principles of Protein Conformation. New York:

    Plenum Press

    . pp. 599–623.

    ISBN

     

    978-0-306-43131-9

    .

    LCCN

     

    89008555

    .

  • Nelson DL, Cox MM (2000).

    Lehninger Principles of Biochemistry

    (3rd ed.).

    Worth Publishers

    .

    ISBN

     

    978-1-57259-153-0

    .

    LCCN

     

    99049137

    .

  • Meierhenrich U

    (2008).

    Amino acids and the asymmetry of life

    (PDF). Berlin:

    Springer Verlag

    .

    ISBN

     

    978-3-540-76885-2

    .

    LCCN

     

    2008930865

    . Archived from the original on 12 January 2012.CS1 maint: bot: original URL status unknown (

    link

    )

External links[

edit

]

  • Media related to

    Amino acid

    at Wikimedia Commons

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