NADP-DEPENDENT ALCOHOL DEHYDROGENASES IN BACTERIA AND YEAST - PURIFICATION AND PARTIAL CHARACTERIZATION OF THE ENZYMES FROM ACINETOBACTER-CALCOACETICUS AND SACCHAROMYCES-CEREVISIAE

An NADP-dependent constitutive alcohol dehydrogenase that can oxidize hexan-1-ol was detected in several Gram-positive and Gram-negative eub acteria and in two yeasts. The enzyme was purified to homogeneity from Acinetobacter calcoaceticus NCIB 8250 and from Saccharomyces cerevisi ae D273-10B. The bacterial enzyme appears to be a tetramer of subunit M(r) 40 300 and the yeast enzyme appears to be a monomer of subunit M( r) 43 500. The N-terminal amino acid sequence of the bacterial enzyme has 34% identity with part of the sequence of a fermentative alcohol d ehydrogenase from Escherichia coli. The pI value of the bacterial enzy me was 5.7 and the pH optimum was 10.2. Both the bacterial and yeast e nzymes were shown to transfer the pro-R hydrogen to/from NADP(H). The substrate specificities of the two enzymes were similar to each other, both oxidizing primary alcohols and some diols, but not secondary alc ohols. The maximum velocities of both enzymes were with pentan-1-ol as substrate and there was very low activity with ethanol; the maximum s pecificity constants were found with primary alcohols containing six t o eight carbon atoms. Neither enzyme was significantly inhibited by me tal-binding agents but some thiol-blocking compounds inhibited them. I t appears that these two alcohol dehydrogenases, one prokaryotic and o ne eukaryotic, are structurally, kinetically and functionally differen t from members of the major known groups of alcohol dehydrogenases.