title: Substrate range of acetohydroxy acid synthase I from Escherichia coli in the stereoselective synthesis of alpha-hydroxy ketones.
abstract: Acetohydroxy acid synthase I appears to be the most effective of the AHAS isozymes found in Escherichia coli in the chiral synthesis of phenylacetyl carbinol from pyruvate and benzaldehyde. We report here the exploration of a range of aldehydes as substrates for AHAS I and demonstrate that the enzyme can accept a wide variety of substituted benzaldehydes, as well as heterocyclic and heteroatomic aromatic aldehydes, to produce chiral carbinols. The active site of AHAS I does not appear to impose serious steric constraints on the acceptor substrate. The influence of electronic effects on the reaction has been probed using substituted benzaldehydes as substrates. The electrophilicity of the aldehyde acceptor substrates is most important to their reactivity, but the lipophilicity of substituents also affects their reactivity. AHAS I is an effective biosynthetic platform for production of a variety of alpha-hydroxy ketones, compounds with considerable potential as pharmacological precursors.
authors.affiliation: Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
authors.forename: Stanislav
authors.initials: S
authors.lastname: Engel
authors.forename: Maria
authors.initials: M
authors.lastname: Vyazmensky
authors.forename: Dvora
authors.initials: D
authors.lastname: Berkovich
authors.forename: Ze'ev
authors.initials: Z
authors.lastname: Barak
authors.forename: David M
authors.initials: DM
authors.lastname: Chipman
mesh_terms: D000095:Acetolactate Synthase / Q000737:chemistry*; D000447:Aldehydes / Q000737:chemistry*; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology*; D007659:Ketones / Q000138:chemical synthesis*; D007700:Kinetics; D012680:Sensitivity and Specificity; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: D000447:Aldehydes; D007659:Ketones; D000095:Acetolactate Synthase