P33: An enoate reductase from Lactobacillus casei for biocatalytic reduction of carbon-carbon double bond

Carbon-carbon double bond of α, β-unsaturated carbonyl compounds can be reduced by enoate reductase, which is an important reaction in fine chemical synthesis. An enoate reductase gene from Lactobacillis casei str zhang was cloned into pET21a (+) and expressed in Escherichia coli BL21 (DE3) host cells. The enzyme (LacER) was purified by ammonium sulfate precipitation and treatment in an acidic buffer. The enzyme showed a maximum activity at pH 8.0. The optimum temperature of the enzyme was at 35°C. LacER was stable below 60°C and lost its activity completely at 65°C after incubation for 1 hr. The enzyme was active toward aliphatic α,β-unsaturated aldehydes and kenones. Substituted groups of cyclic α,β-unsaturated ketones and its ring size have great effects on the enzyme activity. The enoate reductase (LacER) might be a promising biocatalyst for asymmetric reduction of α,β-unsaturated carbonyl compounds, that is further explored in our laboratory.