Biological Preparation For Chiral Hydroxy Ketone Ester

(R)-2-hydroxy-4-phenyl ethyl butyrate [(R)-EHPB] is an important chiral intermediates, is used in synthesis of a variety of angiotensin converting enzyme (ACE) inhibitors. In this study, we obtained a high catalytic ability through KE1screening ketone reductase, and studied its enzymatic properties. Research shows that: KEl with the best reactivity at pH6.0and50℃; more stable at20℃, at30℃and40℃have short half-life,6h and1h, respectively; In2mL of water phase reaction system, the use of glucose dehydrogenase (GDH) containing KE1and whole cells, catalytic reduction EOPB, without adding extra NAPDH, turn10mM EOPB completely (conversion rate>99%, ee>99%); When will the substrate concentration increased to30mM, after12h reaction conversion rate is only38.3%, the enzyme’s stability is very poor, need to be modified.(R)-3-hydroxy ethyl butyrate [(R)-EHB] as a kind of chiral intermediates, to be prepare for many chiral drugs. Poly3-hydroxy ethyl butyrate (PHB) is obtained by EHB of transesterification polycondensation can be used to control the white pollution. Experimental screening got a ketone reductase KE31, acetyl ethyl acetate showed better catalytic performance, optimal activity of KE31in pH7.0, between30℃and40℃enzyme activity change smoothly. KE31and glucose dehydrogenase (GDH) co-expressed in E.coli to build whole-cell catalyst. Polypropylene imine fixed all the cells did not show good stability, even worse than no fixed all cells. Using free whole cell, under25mL reaction system, the substrate concentration reaches1M, the reaction conversion rate can reach99%above.