Open AccessEvidence for oxidative thiolytic cleavage of acetoin in Pelobacter carbinolicus analogous to aerobic oxidative decarboxylation of pyruvate
Author(s) -
Oppermann Fred Bernd,
Steinbüchel Alexander,
Schlegel Hans G.
Publication year - 1989
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1989.tb03429.x
Subject(s) - oxidative decarboxylation , oxidative phosphorylation , acetoin , chemistry , decarboxylation , oxidative cleavage , biochemistry , catalysis , fermentation
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: metronidazol oxidoreductase activity. As shown by reconstitution experiments methylviologen reduction was dependent on the presence of a light‐brownish protein ( M r 220 000 ± 10 000); metronidazol reduction was in addition dependent on the presence of a dark‐brownish protein ( M r 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.