PURIFICATION AND CHARACTERIZATION OF THE E1 COMPONENT OF THE CLOSTRIDIUM-MAGNUM ACETOIN DEHYDROGENASE ENZYME-SYSTEM

In Clostridium magnum strain Wo Bd P1 the formation of the enzyme comp onents of the acetoin dehydrogenase enzyme system E1 (acetoin:2,6-dich lorophenolindophenol oxidoreductase Ao:DCPIP OR), E2 (dihydrolipoamide acetyltransferase DHLTA) and E3 (dihydrolipoamide dehydrogenase DHLDH ) were induced during growth on acetoin. Ao:DCPIP OR was purified from acetoin-grown cells in two steps by chromatography on DEAE-Sephacel a nd on Mono Q HR. Native Ao:DCPIP OR exhibited a M(r) of 138,000; it co nsisted of two different subunits of M(r) alpha 38,500 and M(r) beta 3 4,000, and it occurred most probably in a tetrameric alpha2beta2 struc ture. The N-terminal amino acid sequences of the alpha- and beta-subun its revealed homologies to the N-termini of the corresponding subunits of Ao:DCPIP OR from Pelobacter carbinolicus and from Alcaligenes eutr ophus; furthermore, the N-terminus of the beta-subunit exhibited homol ogies to the N-termini of beta-subunits from different 2-oxo acid dehy drogenases.