title: Examination of a reaction intermediate in the active site of riboflavin synthase.
abstract: The riboflavin synthase catalyzed reaction proceeds through a pentacyclic intermediate of undetermined stereochemistry. Calculations at the B3LYP/6-31G(d) level of theory indicate that the trans pentacyclic structure is favored over the cis by 3.3kcal/mol. A model of the the trans, but not the cis, pentacycle in the enzyme active site shows good fitness and the availability of highly conserved protein residues for catalytic interactions. The model of the trans intermediate complements the model of the two substrates in the active site and allows for a hypothetical mechanism of the roles of specific protein residues in catalysis to be proposed.
authors.affiliation: DuPont Agricultural Products, Stine-Haskell Research Center, 1094 Elkton Road, Post Office Box 30, Newark, DE 19714, USA. ya-jun.zheng@usa.dupont.com
authors.forename: Ya-Jun
authors.initials: YJ
authors.lastname: Zheng
authors.forename: Douglas B
authors.initials: DB
authors.lastname: Jordan
authors.forename: Der-Ing
authors.initials: DI
authors.lastname: Liao
mesh_terms: D001665:Binding Sites; D002384:Catalysis; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D012258:Riboflavin Synthase / Q000737:chemistry* / Q000378:metabolism*; D013237:Stereoisomerism
chemical_list: D012258:Riboflavin Synthase