Purification and properties of a NAD-linked 1,2-propanediol dehydrogenase from propane-grown Pseudomonas fluorescens NRRL B-1244.

NAD-dependent 1,2-propanediol dehydrogenase (EC 1.1.1.4) activity was detected in cell-free crude extracts of various propane-grown bacteria. The enzyme activity was much lower in 1-propanol-grown cells than in propane-grown cells of Pseudomonas fluorescens NRRL B-1244, indicating that the enzyme may be inducible by metabolites of propane subterminal oxidation. 1,2-Propanediol dehydrogenase was purified from propane-grown Ps. fluorescens NRRL B-1244. The purified enzyme fraction shows a single-protein band upon acrylamide gel electrophoresis and has a molecular weight of 760,000. It consists of 10 subunits of identical molecular weight (77,600). It oxidizes diols that possess either two adjacent hydroxy groups, or a hydroxy group with an adjacent carbonyl group. Primary and secondary alcohols are not oxidized. The pH and temperature optima for 1,2-propanediol dehydrogenase are 8.5 and 20-25 degrees C, respectively. The activation energy calculated is 5.76 kcal/mol. 1,2-Propanediol dehydrogenase does not catalyze the reduction of acetol or acetoin in the presence of NADH (reverse reaction). The Km values at 25 degrees C, pH 7.0, buffer solution for 1,2-propan1,2-propanediol dehydrogenase are 8.5 and 20-25 degrees C, respectively. The activation energy calculated is 5.76 kcal/mol. 1,2-Propanediol dehydrogenase does not catalyze the reduction of acetol or acetoin in the presence of NADH (reverse reaction). The Km values at 25 degrees C, pH 7.0, buffer solution for 1,2-propan1,2-propanediol dehydrogenase are 8.5 and 20-25 degrees C, respectively. The activation energy calculated is 5.76 kcal/mol. 1,2-Propanediol dehydrogenase does not catalyze the reduction of acetol or acetoin in the presence of NADH (reverse reaction). The Km values at 25 degrees C, pH 7.0, buffer solution for 1,2-propanediol and NAD are 2 X 10(-2) and 9 X 10(-5) M, respectively. The 1,2-propanediol dehydrogenase activity was inhibited by strong thiol reagents, but not by metal-chelating agents. The amino acid composition of the purified enzyme was determined. Antisera prepared against purified 1,2-propanediol dehydrogenase from propane-grown Ps. fluorescens NRRL B-1244 formed homologous precipitin bands with isofunctional enzymes derived from propane-grown Arthrobacter sp. NRRL B-11315, Nocardia paraffinica ATCC 21198, and Mycobacterium sp. P2y, but not from propane-grown Pseudomonas multivorans ATCC 17616 and Brevibacterium sp. ATCC 14649, or 1-propanol-grown Ps. fluorescens NRRL B-1244. Isofunctional enzymes derived from methane-grown methylotrophs also showed different immunological and catalytic properties.