title: Noncanonical reactions of flavoenzymes.
abstract: Enzymes containing flavin cofactors are predominantly involved in redox reactions in numerous cellular processes where the protein environment modulates the chemical reactivity of the flavin to either transfer one or two electrons. Some flavoenzymes catalyze reactions with no net redox change. In these reactions, the protein environment modulates the reactivity of the flavin to perform novel chemistries. Recent mechanistic and structural data supporting novel flavin functionalities in reactions catalyzed by chorismate synthase, type II isopentenyl diphosphate isomerase, UDP-galactopyranose mutase, and alkyl-dihydroxyacetonephosphate synthase are presented in this review. In these enzymes, the flavin plays either a direct role in acid/base reactions or as a nucleophile or electrophile. In addition, the flavin cofactor is proposed to function as a "molecular scaffold" in the formation of UDP-galactofuranose and alkyl-dihydroxyacetonephosphate by forming a covalent adduct with reaction intermediates.
authors.affiliation: Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA. psobrado@vt.edu.
authors.forename: Pablo
authors.initials: P
authors.lastname: Sobrado
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000737:chemistry / Q000378:metabolism; D019748:Carbon-Carbon Double Bond Isomerases / Q000737:chemistry / Q000378:metabolism; D002384:Catalysis; D004798:Enzymes / Q000737:chemistry / Q000378:metabolism*; D005415:Flavins / Q000737:chemistry / Q000378:metabolism*; D045782:Hemiterpenes; D019751:Intramolecular Transferases / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D019761:Phosphorus-Oxygen Lyases / Q000737:chemistry / Q000378:metabolism
chemical_list: D004798:Enzymes; D005415:Flavins; D045782:Hemiterpenes; D019883:Alkyl and Aryl Transferases; C019654:alkylglycerone-phosphate synthase; C019895:chorismate synthase; D019761:Phosphorus-Oxygen Lyases; D019748:Carbon-Carbon Double Bond Isomerases; C021453:isopentenyldiphosphate delta-isomerase; D019751:Intramolecular Transferases; C098051:UDP-galactopyranose mutase