Asymmetric Biosynthesis Of α-Hydroxyphenylacetic Acid

(R)/(S)-HPA and their derivatives are valuable chiral pharmaceutical intermediates for the production of semi-synthetic penicillin,cephalosporin and antiobesity agents.(R)/(S)-HPA are mainly prepared through asymmetric chemo-synthesis and kinetic resolution.Asymmetric biosynthesis with its metrics of mild reaction condition and high selectivity is becoming increasingly important for the synthesis of chiral drug.Therefore,biosynthesis of(R)/(S)-HPA from potential chiral compound PGA was studied in these paper.After screening from 38 strains obtained from CCCCM or stored in our institute, Scl0 and Lk5 with high ability of transforming PGA tO(R)/(S)-HPA respectively and with high enantioselectivity were selected as original strains.Through UV mutagenesis and microwave mutagenesis,mutant SclO.9.48 characterized by high endurance of substrate was obtained.The endurance substrate concentration increased from 10mmol/L to 60mmol/L.After a series of research on culture medium and bioreduction conditions.the yield of HPA of 81.5% and e.e.of R—HPA of 9.5%determined by HPLC and HPCE were achievedf Biotransformation conditions:initial substrate concentration,60mmol/L;shake speed,1 40rmp;pH,6.6,temperature,34℃;reaction time,54 hours).Moreover,the molecular weight of product was determined by HPLC-MS,which demonstrated that the product was HPA.Through domestication,strain Lk5.1 biosynthesizing S-HPA was obtained.After the optimization of carbon and nitrogen source in the medium culture,as well as reduction conditions,the S-HPA yield of 80.7%and e.e.of 99.7%could be obtained,and the optimum bioreduction conditions were shake speed 160rmp,temperature 34℃,pH7.0,initial substrate concentration 40mmol/L and 48 hours for reduction.Co-culture of Lk5.1 and SclO.9.48 was successfully applied for biosynthesis of R—HPA.The product yield and production rate significantly increased compared to those in pure culture of Sc10.9.48...