Aspartic acid (symbol Asp or D; the ionic form is known as aspartate), is an α-
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha a ...
that is used in the biosynthesis of proteins.
Like all other amino acids, it contains an amino group and a carboxylic acid. Its α-amino group is in the protonated –NH form under physiological conditions, while its α-carboxylic acid group is deprotonated −COO
− under physiological conditions. Aspartic acid has an acidic side chain (CH
2COOH) which reacts with other amino acids, enzymes and proteins in the body.
Under physiological conditions (pH 7.4) in proteins the side chain usually occurs as the negatively charged aspartate form, −COO
−.
It is a non-
essential amino acid
An essential amino acid, or indispensable amino acid, is an amino acid that cannot be synthesized from scratch by the organism fast enough to supply its demand, and must therefore come from the diet. Of the 21 amino acids common to all life form ...
in humans, meaning the body can
synthesize it as needed. It is
encoded
In communications and information processing, code is a system of rules to convert information—such as a letter, word, sound, image, or gesture—into another form, sometimes shortened or secret, for communication through a communication ...
by the
codons GAU and GAC.
D-Aspartate is one of two
D-amino acids commonly found in mammals.
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In proteins aspartate sidechains are often hydrogen bonded to form
asx turns or
asx motif The Asx motif is a commonly occurring feature in proteins and polypeptides. It consists of four or five amino acid residues with either aspartate or asparagine as the first residue (residue i). It is defined by two internal hydrogen bonds. One is b ...
s, which frequently occur at the N-termini of
alpha helices
The alpha helix (α-helix) is a common motif in the secondary structure of proteins and is a right hand-helix conformation in which every backbone N−H group hydrogen bonds to the backbone C=O group of the amino acid located four residues ear ...
.
The
L-isomer of Asp is one of the 22
proteinogenic amino acid
Proteinogenic amino acids are amino acids that are incorporated biosynthetically into proteins during translation. The word "proteinogenic" means "protein creating". Throughout known life, there are 22 genetically encoded (proteinogenic) amino aci ...
s, i.e., the building blocks of
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
s. Aspartic acid, like
glutamic acid, is classified as an acidic amino acid, with a
pKa of 3.9, however in a peptide this is highly dependent on the local environment, and could be as high as 14. Asp is pervasive in biosynthesis.
Discovery
Aspartic acid was first discovered in 1827 by
Auguste-Arthur Plisson and
Étienne Ossian Henry
Étienne-Ossian Henry (27 November 1798 in Paris – 26 August 1873) was a French chemist, son of Nöel Étienne Henry (1769–1832), and trained by his father, who was director of the Central Pharmacy of the Parisian hospitals and professor ...
by
hydrolysis
Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile.
Biological hydrolys ...
of
asparagine
Asparagine (symbol Asn or N) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated −NH form under biological conditions), an α-carboxylic acid group (which is in the depro ...
, which had been isolated from
asparagus
Asparagus, or garden asparagus, folk name sparrow grass, scientific name ''Asparagus officinalis'', is a perennial flowering plant species in the genus '' Asparagus''. Its young shoots are used as a spring vegetable.
It was once classified in ...
juice in 1806. Their original method used
lead hydroxide Lead hydroxide may refer to:
* Lead(II) hydroxide
* Lead(IV) hydroxide
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