title: Evidence for oxidative thiolytic cleavage of acetoin in Pelobacter carbinolicus analogous to aerobic oxidative decarboxylation of pyruvate.
abstract: Dihydrolipoamide dehydrogenase and dihydrolipoamide acetyltransferase were formed when Pelobacter carbinolicus strain GraBd1 was grown on acetoin. The specific activities of these enzymes amounted to 0.50 and 28.7 U/mg protein, respectively. The crude extract catalyzed the CoASH- and NAD+-dependent formation of acetyl-CoA from acetoin and methylacetoin. From ethylene glycol-grown cells these activities were absent. Crude extracts also exhibited acetoin: methyl viologen and acetoin: metronidazole oxidoreductase activity. As shown by reconstitution experiments methylviologen reduction was dependent on the presence of a light-brownish protein (Mr 220,000 +/- 10,000); metronidazole reduction was in addition dependent on the presence of a dark-brownish protein (Mr 4,900 +/- 800), which is probably a ferredoxin. However, both components were synthesized constitutively. We discussed a model for oxidative-thiolytic cleavage of acetoin which is analogous to the reaction of the pyruvate dehydrogenase enzyme complex rather than to pyruvate: ferredoxin oxidoreductase.
authors: Institut für Mikrobiologie der Georg-August-Universität zu Göttingen, F.R.G.
authors: F B
authors: FB
authors: Oppermann
authors: A
authors: A
authors: Steinbüchel
authors: H G
authors: HG
authors: Schlegel
mesh_terms: D000093:Acetoin / Q000378:metabolism*; D000105:Acetyl Coenzyme A / Q000096:biosynthesis; D000123:Acetyltransferases / Q000378:metabolism; D001421:Bacteria, Anaerobic / Q000378:metabolism*; D002074:Butanones / Q000378:metabolism*; D002845:Chromatography; D003653:Decarboxylation; D008058:Dihydrolipoamide Dehydrogenase / Q000378:metabolism; D051047:Dihydrolipoyllysine-Residue Acetyltransferase; D004591:Electrophoresis, Polyacrylamide Gel; D019855:Ethylene Glycol; D005026:Ethylene Glycols / Q000378:metabolism; D008795:Metronidazole / Q000378:metabolism; D008956:Models, Chemical; D010084:Oxidation-Reduction; D011768:Pyruvate Dehydrogenase Complex; D011773:Pyruvates / Q000378:metabolism*; D019289:Pyruvic Acid
chemical_list: D002074:Butanones; D005026:Ethylene Glycols; D011768:Pyruvate Dehydrogenase Complex; D011773:Pyruvates; D008795:Metronidazole; D000105:Acetyl Coenzyme A; D019289:Pyruvic Acid; D000093:Acetoin; D008058:Dihydrolipoamide Dehydrogenase; D000123:Acetyltransferases; D051047:Dihydrolipoyllysine-Residue Acetyltransferase; D019855:Ethylene Glycol