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

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.

↑ 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. PMID 4719123. doi:10.1021/bi00739a015.
Pearl, Phillip L., Parviz, Mahsa, Hodgeman, Ryan, Gibson, K. Michael. GABA-transaminase deficiency. In: Reimschisel T (ed.) MedLink Neurology. San Diego, California: MedLink Corporation. http://medlink.com/article/gaba-transaminase_deficiency

anabolism:	Histidine decarboxylase
catabolism:	Histamine N-methyltransferase Diamine oxidase

anabolism:	Tyrosine hydroxylase Aromatic L-amino acid decarboxylase Dopamine beta-hydroxylase Phenylethanolamine N-methyltransferase
catabolism:	Catechol-O-methyl transferase Monoamine oxidase A B

anabolism:	Glutamate decarboxylase
catabolism:	4-aminobutyrate transaminase

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

Enzymes
Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Catalytically perfect enzyme Coenzyme Cofactor Enzyme catalysis
Regulation	Allosteric regulation Cooperativity Enzyme inhibitor
Classification	EC number Enzyme superfamily Enzyme family List of enzymes
Kinetics	Enzyme kinetics Eadie–Hofstee diagram Hanes–Woolf plot Lineweaver–Burk plot Michaelis–Menten kinetics
Types	EC1 Oxidoreductases (list) EC2 Transferases (list) EC3 Hydrolases (list) EC4 Lyases (list) EC5 Isomerases (list) EC6 Ligases (list)

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