초록
<P><I>tert</I>-Butyl (3<I>R</I>,5<I>S</I>)-6-chloro-3,5-dihydroxyhexanoate ((3<I>R</I>,5<I>S</I>)-CDHH) is a key intermediate of atorvastatin and rosuvastatin synthesis. Carbonyl reductase <I>Rt</I>SCR9 from <I>Rhodosporidium toruloides</I> exhibited excellent activity toward <I>tert</I>-butyl (<I>S</I>)-6-chloro-5-hydroxy-3-oxohexanoate ((<I>S</I>)-CHOH). For the activity of <I>Rt</I>SCR9 to be improved, random mutagenesis and site-saturation mutagenesis were performed. Three positive mutants were obtained (mut-Gln95Asp, mut-Ile144Lys, and mut-Phe156Gln). These mutants exhibited 1.94-, 3.03-, and 1.61-fold and 1.93-, 3.15-, and 1.97-fold improvement in the specific activity and <I>k</I><SUB>cat</SUB>/<I>K</I><SUB>m</SUB>, respectively. Asymmetric reduction of (<I>S</I>)-CHOH by mut-Ile144Lys coupled with glucose dehydrogenase was conducted. The yield and enantiomeric excess of (3<I>R</I>,5<I>S</I>)-CDHH reached 98 and 99%, respectively, after 8 h bioconversion in a single batch reaction with 1 M (<I>S</I>)-CHOH, and the space-time yield reached 542.83 mmol L<SUP>–1</SUP> h<SUP>–1</SUP> g<SUP>–1</SUP> wet cell weight. This study presents a new carbonyl reductase for efficient synthesis of (3<I>R</I>,5<I>S</I>)-CDHH.</P><P><B>Graphic Abstract</B><BR><IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jafcau/2017/jafcau.2017.65.issue-18/acs.jafc.7b00866/production/images/medium/jf-2017-008664_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jf7b00866'>ACS Electronic Supporting Info</A></P>