Stereocomplementary bioreduction of alpha,beta-unsaturated dicarboxylic acids and dimethyl esters using enoate reductases: enzyme- and substrate-based stereocontrol.

Asymmetric bioreduction of alpha,beta-unsaturated dicarboxylic acids, such as 2-methylmaleic/fumaric and 2-methylenesuccinic acid, as well as the corresponding dimethyl esters, using three cloned enoate reductases furnished 2-methylsuccinic acid or dimethyl 2-methylsuccinate, respectively. Opposite stereoisomeric products were obtained in up to >99% ee either by choice of the enzyme or by using E/Z-configurated substrates. Cofactor-recycling systems (NADH/FDH/formate, NADH/GDH/glucose or NADPH/G6PDH/glucose-6-phosphate) only worked in presence of a divalent metal ion, such as Ca2+, Mg2+, or Zn2+.