Accepted name: acetolactate synthase
Reaction: 2 pyruvate = 2-acetolactate + CO2
Glossary: thiamine diphosphate = 3-[(4-amino-2-methylpyrimidin-5-yl)methyl]-5-(2-diphosphoethyl)-4-methyl-1,3-thiazolium
Other name(s): α-acetohydroxy acid synthetase; α-acetohydroxyacid synthase; α-acetolactate synthase; α-acetolactate synthetase; acetohydroxy acid synthetase; acetohydroxyacid synthase; acetolactate pyruvate-lyase (carboxylating); acetolactic synthetase
Systematic name: pyruvate:pyruvate acetaldehydetransferase (decarboxylating)
Comments: This enzyme requires thiamine diphosphate. The reaction shown is in the pathway of biosynthesis of valine; the enzyme can also transfer the acetaldehyde from pyruvate to 2-oxobutanoate, forming 2-ethyl-2-hydroxy-3-oxobutanoate, also known as 2-aceto-2-hydroxybutanoate, a reaction in the biosynthesis of isoleucine.
1.  Bauerle, R.H., Freundlich, M., Størmer, F.C. and Umbarger, H.E. Control of isoleucine, valine and leucine biosynthesis. II. Endproduct inhibition by valine of acetohydroxy acid synthetase in Salmonella typhimurium. Biochim. Biophys. Acta 92 (1964) 142–149. [PMID: 14243762]
2.  Huseby, N.E., Christensen, T.B., Olsen, B.R. and Størmer, F.C. The pH 6 acetolactate-forming enzyme from Aerobacter aerogenes. Subunit structure. Eur. J. Biochem. 20 (1971) 209–214. [PMID: 5560406]
3.  Størmer, F.C., Solberg, Y. and Hovig, T. The pH 6 acetolactate-forming enzyme from Aerobacter aerogenes. Molecular properties. Eur. J. Biochem. 10 (1969) 251–260. [PMID: 5823101]
4.  Barak, Z., Chipman, D.M. and Gollop, N. Physiological implications of the specificity of acetohydroxy acid synthase isozymes of enteric bacteria. J. Bacteriol. 169 (1987) 3750–3756. [PMID: 3301814]
[EC created 1972 as EC, transferred 2002 to EC]

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