title: Electron-transferring flavoprotein of Peptostreptococcus elsdenii that functions in the reduction of acrylyl-coenzyme A.
abstract: In Peptostreptococcus elsdenii, a three-component flavoprotein electron transfer system catalyzes the oxidation of lactate and the reduction of crotonyl-coenzyme A (CoA). Spectral evidence showed that D-lactate dehydrogenase, when reduced by D-lactate, was able to reduce butyryl-CoA dehydrogenase, but only in the presence of the electron-transferring flavoprotein. Reduced nicotinamide adenine dinucleotide could replace reduced D-lactate dehydrogenase. A reconstituted system, containing the three partially purified enzymes, excess D-lactate, and a limiting amount of crotonyl-CoA, reduced the crotonyl-CoA to butyryl-CoA, but only if all components were present. The electron-transferring flavoprotein activity, purified 22-fold, was separated into two major flavoprotein components, A and B, after polyacrylamide gel electrophoresis. Elution of the proteins and subsequent kinetic assays of the eluates showed that component B catalyzes the reduction of butyryl-CoA dehydrogenase by reduced D-lactate dehydrogenase, whereas component A does not. Both A and B catalyzed the reduction of butyryl-CoA dehydrogenase by reduced nicotinamide adenine dinucleotide. The results suggest that the D-lactate dehydrogenase-dependent reduction involves a heretofore unrecognized component of the electron-transferring protein group which may utilize an unusual flavin, 6-hydroxy-7,8-dimethyl-10-(ribityl-5'-adenosine diphosphate)-isoalloxazine.
mesh_terms: D000179:Acrylates / Q000378:metabolism; D000215:Acylation; D002087:Butyrates / Q000378:metabolism; D003065:Coenzyme A / Q000378:metabolism*; D003437:Crotonates / Q000378:metabolism; D004579:Electron Transport; D005420:Flavoproteins / Q000378:metabolism*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D007773:Lactates / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D010462:Peptostreptococcus / Q000201:enzymology / Q000378:metabolism*; D013237:Stereoisomerism
chemical_list: D000179:Acrylates; D002087:Butyrates; D003437:Crotonates; D005420:Flavoproteins; D007773:Lactates; D009243:NAD; D010088:Oxidoreductases; D007770:L-Lactate Dehydrogenase; D003065:Coenzyme A