α-Aminobutyric acid (AABA), also known as homoalanine in biochemistry, is a non-proteinogenic alpha amino acid with chemical formula C₄H₉NO₂. The straight two carbon side chain is one carbon longer than alanine, hence the prefix homo-. The

conjugate base A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid gives a proton () to a base—in other words, it is a base with a hydrogen ion added to it, as it loses a hydrogen ion in the reve ...

of α-aminobutyric acid is the

carboxylate In organic chemistry, a carboxylate is the conjugate base of a carboxylic acid, (or ). It is an anion, an ion with negative charge. Carboxylate salts are salts that have the general formula , where M is a metal and ''n'' is 1, 2,... ...

α-aminobutyrate. Homoalanine is biosynthesized by transaminating oxobutyrate, a metabolite in

isoleucine Isoleucine (symbol Ile or I) 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 ...

biosynthesis. It is used by

nonribosomal peptide Nonribosomal peptides (NRP) are a class of peptide secondary metabolites, usually produced by microorganisms like bacterium, bacteria and fungi. Nonribosomal peptides are also found in higher organisms, such as nudibranchs, but are thought to be ma ...

synthases. One example of a nonribosomal peptide containing homoalanine is

ophthalmic acid Ophthalmic acid (OPH), also known as ophthalmate (chemically L-γ-glutamyl-L-α-aminobutyrylglycine), is a tripeptide analog of glutathione. However, instead of the cysteine essential for many of glutathione's diverse functions, it contains L-2-am ...

, which was first isolated from calf lens. α-Aminobutyric acid is one of the three

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, the same number of atoms of each element (chemistry), element – but distinct arrangements of atoms in space. ''Isomerism'' refers to the exi ...

s of aminobutyric acid. The two other are the neurotransmitter

γ-aminobutyric acid GABA (gamma-aminobutyric acid, γ-aminobutyric acid) is the chief inhibitory neurotransmitter in the developmentally mature mammalian central nervous system. Its principal role is reducing neuronal excitability throughout the nervous system. GA ...

(GABA) and β-aminobutyric acid (BABA) which is known for inducing

plant disease resistance Plant disease resistance protects plants from pathogens in two ways: by pre-formed structures and chemicals, and by infection-induced responses of the immune system. Relative to a susceptible plant, disease resistance is the reduction of pathogen ...

. This amino acid has been detected in meteorites.

References

{{DEFAULTSORT:Aminobutyric Acid, Alpha- Alpha-Amino acids GABA analogues