Electron Transfer in Acetohydroxy Acid Synthase as a Side Reaction of Catalysis. Implications for the Reactivity and Partitioning of the Carbanion/Enamine Form of (α-Hydroxyethyl)thiamin Diphosphate in a “Nonredox” Flavoenzyme

• Published in: Biochemistry (Easton) Vol. 43; no. 27; pp. 8652 - 8661
• Main Authors: Tittmann, Kai, Schröder, Kathrin, Golbik, Ralph, McCourt, Jennifer, Kaplun, Alexander, Duggleby, Ronald G, Barak, Ze'ev, Chipman, David M, Hübner, Gerhard
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 13.07.2004
• Subjects: Acetolactate Synthase - chemistry; Acetolactate Synthase - metabolism; Catalysis; Electron Transport; Flavin-Adenine Dinucleotide - metabolism; Kinetics; Magnetic Resonance Spectroscopy; Models, Molecular; Molecular Structure; Oxygen - metabolism; Pyruvic Acid - metabolism; Spectrum Analysis; Thiamine Pyrophosphate - analogs & derivatives; Thiamine Pyrophosphate - chemistry; Thiamine Pyrophosphate - metabolism

Acetohydroxy acid synthases (AHAS) are thiamin diphosphate- (ThDP-) and FAD-dependent enzymes that catalyze the first common step of branched-chain amino acid biosynthesis in plants, bacteria, and fungi. Although the flavin cofactor is not chemically involved in the physiological reaction of AHAS, i...