title: How an enzyme answers multiple-choice questions.
abstract: Acetohydroxyacid synthase (AHAS) is the first common enzyme in the pathway for the biosynthesis of branched-chain amino acids. Interest in the enzyme has escalated over the past 20 years since it was discovered that AHAS is the target of the sulfonylurea and imidazolinone herbicides. However, several questions regarding the reaction mechanism have remained unanswered, particularly the way in which AHAS "chooses" its second substrate. A new method for the detection of reaction intermediates enables calculation of the microscopic rate constants required to explain this phenomenon.
authors.affiliation: School of Molecular and Microbial Sciences, University of Queensland, St Lucia, Brisbane, QLD 4072, Australia.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: McCourt
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Duggleby
mesh_terms: D000095:Acetolactate Synthase / Q000378:metabolism*; D015394:Molecular Structure; D019289:Pyruvic Acid / Q000378:metabolism; D013379:Substrate Specificity; D013835:Thiamine Pyrophosphate / Q000737:chemistry / Q000378:metabolism*
chemical_list: D019289:Pyruvic Acid; D000095:Acetolactate Synthase; D013835:Thiamine Pyrophosphate