Abstract

A novel 1,3-propanediol oxidoreductase (YqhD-1) found in Klebsiella oxytoca M5al was purified to homogeneity with a his-tag on a Ni-NTA column. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of the purified protein showed a molecular weight of 42 kDa. When YqhD-1 was tested as a dehydrogenase, the optimal pH was 11 and the optimal temperature was 37°C. Both Zn²⁺ and Fe²⁺ promoted YqhD-1 activity, whereas Mn²⁺, Ni²⁺, SO₄^2- and EDTA markedly inhibited YqhD-1 activity. Broad substrate specificity was observed for YqhD-1 with activity for several alcohols, including 1,3-propanediol, 1,2-propanediol, propanol, glycerol, 1-butanol, 1,3-butanediol and isopentanol. However, the enzyme preferred high carbon number alcohols such as 1-butanol and isopentanol. When tested as an aldehyde reductase, YqhD-1 could convert acetaldehyde and propaldehyde to their respective alcohols. When 1,3-PD and propaldehyde served as substrates, the apparent Km values of the enzyme for NADP and NADPH were 0.14 and 0.64 mM, respectively.

Key words: Klebsiella oxytoca, 1,3-propanediol oxidoreductase, purification, YqhD.