A carbonyl reductase from Candida parapsilosis ATCC 7330: Substrate selectivity and enantiospecificity
Candida parapsilosis ATCC 7330, a rich source of highly stereospecific oxidoreductases, catalyzes oxidation-reduction of a plethora of compounds yielding industrially important intermediates. An (S)-specific carbonyl reductase (SRED) purified and characterized from this yeast is reported here. (R)-specific carbonyl reductase (CpCR) was reported by us earlier. SRED asymmetrically reduces ketones with excellent enantiospecificity (ee > 99%) and α-ketoesters with higher catalytic activity but moderate enantiospecificity (ee 70%) in the presence of NADPH. Minimal activity is shown towards reduction of aldehydes. While the reduction of α-ketoesters with SRED can occur with either NADPH or NADH, for ketone reduction SRED requires NADPH specifically. SRED with subunit molecular weight of 30 kDa shows optimal activity at pH 5.0 and 25 oC, and its activity is affected by Cu2+. Taken together, SRED and CpCR offer substrates which on asymmetric reduction give products of opposite absolute configurations.