Studies on the mechanism of Mycobacterium smegmatis L-lactate oxidase. 5-Deazaflavin mononucleotide as a coenzyme analogue.
Apo-lactic oxidase from Mycobacterium smegmatis reconstituted with the deazaisoalloxazine analogue of FMN, 5-deazaFMN, undergoes reduction by L-lactate but not catalytic reoxidation by O2. The rate of deazaFMN-holo-enzyme reduction by substrate is 1.1 min-1. With L-[alpha-3-H]-lactate, direct tritium transfer to enzyme-bound deazaFMN occurs during reduction. No evidence for a stable covalent lactate-deazaFMN adduct has been obtained. The deaza-FMNH2-enzyme is reoxidized extremely slowly by O2, consistent with the sluggish nonenzymatic reaction of deaza-FMNH2 with oxygen. On the other hand, addition of pyruvate to the deazaFMNH2-enzyme causes rapid reoxidation, a process not detected in the absence of enzyme.
D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D002850:Chromatography, Gel; D005486:Flavin Mononucleotide / Q000031:analogs & derivatives*; D007700:Kinetics; D007773:Lactates; D009161:Mycobacterium / Q000201:enzymology*; D010084:Oxidation-Reduction; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet; D014316:Tritium
D007773:Lactates; D014316:Tritium; D005486:Flavin Mononucleotide; D000429:Alcohol Oxidoreductases