Efficient Synthesis of (R)-2-Chloro-1-(2,4-dichlorophenyl)ethanol with a Ketoreductase from Scheffersomyces stipitis CBS 6045

摘要

By enzyme screening, a ketoreductase cloned from Scheffersomyces stipitis CBS 6045 and named SsCR was identified that could catalyze the asymmetric hydrogenation of a variety of aromatic ketones. SsCR exhibited a specific activity of 65 Umg(-1) protein and excellent enantioselectivity (99.9% ee) towards the hydrophobic substrate 2-chloro- 1-(2,4-dichlorophenyl) ethanone, which is an intermediate in the synthesis of common antifungal agents such as miconazole, econazole and sertaconazole. The kinetic parameter k(cat)/K-m was 4.51 X 10(3) s(-1)mM(-1), showing the great catalytic efficiency of SsCR towards this substrate. Molecular dynamic simulation results shed light on the higher substrate binding free energy change for this substrate relative to other substrates. Based on the good catalytic properties of SsCR, (R)-2-chloro-1-(2,4-dichlorophenyl) ethanol could be obtained with a space-time yield (STY) of up to 268 gL(-1)d(-1) without any additional cofactor required in the reductive reaction process. On scaling up the bioreaction, the (R)-alcohol was isolated with 88.2% yield and 99.9% ee. The environmental factor (E factor) of this reaction was 7.25 when process water was excluded.