Requires thiamine diphosphate. This enzyme, which belongs to the family of 2-oxo acid dehydrogenase complexes, catalyses the oxidative-hydrolytic cleavage of acetoin to acetaldehyde and acetyl-CoA in many bacterial strains, both aerobic and anaerobic. The enzyme is composed of multiple copies of three enzymic components: acetoin oxidoreductase (E1), dihydrolipoamide acetyltransferase (E2) and dihydrolipoyl dehydrogenase (E3).
The combination of purified Ao:DCPIP OR, dihydrolipoamide dehydrogenase, and dihydrolipoamide acetyltransferase in the presence of thiamine diphosphate and the substrate acetoin or methylacetoin results in a coenzyme A-dependent reduction of NAD
formation of the enzyme components of the acetoin dehydrogenase enzyme system E1, i.e. acetoin:2,6-dichlorophenolindophenol oxidoreductase Ao:DCPIP OR,, E2, i.e. dihydrolipoamide acetyltransferase DHLTA, and E3, i.e. dihydrolipoamide dehydrogenase DHLDH, are induced during growth on acetoin
the enzymes Ao:DCPIP OR, dihydrolipoamide dehydrogenase, and dihydrolipoamide acetyltransferase are induced during growth on acetoin, whereas they are absent or scarcely present in cells grown on a nonacetoinogenic substrate