Sudhakara Sneha, Chadha Anju
Laboratory of Bioorganic Chemistry, Department of Biotechnology, Indian Institute of Technology Madras, Chennai 600 036, India.
Org Biomol Chem. 2017 May 16;15(19):4165-4171. doi: 10.1039/c7ob00340d.
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 the 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 a subunit molecular weight of 30 kDa shows optimal activity at pH 5.0 and 25 °C, and its activity is affected by Cu. Taken together, SRED and CpCR offer substrates which on asymmetric reduction give products of opposite absolute configurations.
近平滑念珠菌ATCC 7330是高度立体特异性氧化还原酶的丰富来源，可催化多种化合物的氧化还原反应，生成具有工业重要性的中间体。本文报道了从该酵母中纯化并表征的一种（S）特异性羰基还原酶（SRED）。我们之前报道过（R）特异性羰基还原酶（CpCR）。在NADPH存在的情况下，SRED以优异的对映体特异性（ee>99%）不对称还原酮类，对α-酮酯具有较高的催化活性，但对映体特异性适中（ee 70%）。对醛的还原显示出最小活性。虽然SRED对α-酮酯的还原可以用NADPH或NADH进行，但对于酮的还原，SRED特别需要NADPH。亚基分子量为30 kDa的SRED在pH 5.0和25°C时显示出最佳活性，其活性受铜的影响。综上所述，SRED和CpCR提供的底物经不对称还原后可得到具有相反绝对构型的产物。
