4-aminobutyrate transaminase

In enzymology, 4-aminobutyrate transaminase (EC 2.6.1.19), also called GABA transaminase or 4-aminobutyrate aminotransferase, is an enzyme that catalyzes the chemical reaction:

4-aminobutanoate + 2-oxoglutarate

\rightleftharpoons

succinate semialdehyde + L-glutamate

Thus, the two substrates of this enzyme are 4-aminobutanoate (GABA) and 2-oxoglutarate. The two products are succinate semialdehyde and L-glutamate.

This enzyme belongs to the family of transferases, specifically the transaminases, which transfer nitrogenous groups. The systematic name of this enzyme class is 4-aminobutanoate:2-oxoglutarate aminotransferase. This enzyme participates in 5 metabolic pathways: alanine and aspartate metabolism, glutamate metabolism, beta-alanine metabolism, propanoate metabolism, and butanoate metabolism. It employs one cofactor, pyridoxal phosphate.

Structural Studies

As of late 2007, 9 structures have been solved for this class of enzymes, with PDB accession codes 1OHV, 1OHW, 1OHY, 1SF2, 1SFF, 1SZK, 1SZS, 1SZU, and 2EO5.

Inhibitors

Main article: GABA transaminase inhibitor

References

↑ Bioassay-guided fractionation of lemon balm (Melissa officinalis L.) using an in vitro measure of GABA transaminase activity. Awad R, Muhammad A, Durst T, Trudeau VL and Arnason JT, Phytother Res., August 2009, volume 23, issue 8, pages 1075-1081, doi:10.1002/ptr.2712

Scott EM, Jakoby WB (1959). "Soluble gamma-aminobutyric-glutamic transaminase from Pseudomonas fluorescens". J. Biol. Chem. 234 (4): 932–936. PMID 13654294.
Aurich H (1961). "Ueber die beta-Alanin-alpha-Ketoglutarat-Transaminase aus Neurospora crassa". Hoppe-Seyler's Z. Physiol. Chem. 326: 25–33. doi:10.1515/bchm2.1961.326.1.25.
Schousboe A, Wu JY, Roberts E (1973). "Purification and characterization of the 4-aminobutyrate:2-ketoglutarate transaminase from mouse brain". Biochemistry 12 (15): 2868–73. doi:10.1021/bi00739a015. PMID 4719123.

External links

4-Aminobutyrate Transaminase at the US National Library of Medicine Medical Subject Headings (MeSH)

Enzymes involved in neutrotransmission

monoamine

histidine → histamine

anabolism:	Histidine decarboxylase

catabolism:	Histamine N-methyltransferase Diamine oxidase

tyrosine→dopamine→epinephrine

anabolism:	Tyrosine hydroxylase Aromatic L-amino acid decarboxylase Dopamine beta-hydroxylase Phenylethanolamine N-methyltransferase

catabolism:	Catechol-O-methyl transferase Monoamine oxidase

glutamate→GABA

anabolism:	Glutamate decarboxylase

catabolism:	4-aminobutyrate transaminase

tryptophan→serotonin→melatonin

arginine→NO

Nitric oxide synthase (NOS1, NOS2, NOS3)

choline→Acetylcholine

anabolism:	Choline acetyltransferase

catabolism:	Cholinesterase (Acetylcholinesterase, Butyrylcholinesterase)

Transferase: nitrogenous groups (EC 2.6)

2.6.1: Transaminases	Aspartate transaminase GOT1 GOT2 Alanine transaminase GABA transaminase Tyrosine aminotransferase Ornithine aminotransferase Branched chain aminotransferase Alanine—glyoxylate transaminase AGXT

2.6.3: Oximinotransferases	Oximinotransferase

2.6.99: Other	Pyridoxine 5'-phosphate synthase

Proteins: enzymes

Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Catalytically perfect enzyme Coenzyme Cofactor Enzyme catalysis Enzyme kinetics Lineweaver–Burk plot Michaelis–Menten kinetics

Regulation	Allosteric regulation Cooperativity Enzyme inhibitor

Classification	EC number Enzyme superfamily Enzyme family List of enzymes

Types	EC1 Oxidoreductases(list) EC2 Transferases(list) EC3 Hydrolases(list) EC4 Lyases(list) EC5 Isomerases(list) EC6 Ligases(list)

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