The purified D-hydantoinase was immobilized on EAH sepharose 4B via the carbodiimide method with a yield of enzyme activity up to 79.44%.The immobilized hydantoinase showed remarkable stability at 4℃.An integrated pr...The purified D-hydantoinase was immobilized on EAH sepharose 4B via the carbodiimide method with a yield of enzyme activity up to 79.44%.The immobilized hydantoinase showed remarkable stability at 4℃.An integrated process of N-carbamoyl-D-phenylalanine(N-D-Phe)synthesis from D,L-5-benzylhydantoin(D,L-BH)catalyzed by immobilized D-hydantoinase coupled with an ion-exchange unit for in situ product removal(ISPR)was established.The variation of pH and conversion in the fixed-bed reactor with or without ISPR was compared at different temperatures,initial substrate concentrations and volumes of adsorbent.Within 24 h,the pH value in the reactor with ISPR could be kept at the alkaline range,which was beneficial to the enzymatic conversion and racemization of L-5-benzyl hydantoinase.This led to a higher overall conversion of 62.725% under optimal operation conditions,an increase of 89.3% compared with the fixed-bed reactor without ISPR.展开更多
Production and accumulation of toxic by-products such as acetic acid can inhibit the growth of recombinant cells and the expression of exogenous gene in E.coli. An anionic exchange resin, A-D 3-1, which is high in ads...Production and accumulation of toxic by-products such as acetic acid can inhibit the growth of recombinant cells and the expression of exogenous gene in E.coli. An anionic exchange resin, A-D 3-1, which is high in adsorption selectivity and capability for acetic acid, was screened from a variety of resins based on its physical and chemical properties.On the scale of shake flask culture, the addition of 1.0 g resin per 30 ml medium was insignificant for the cell growth, however,it could improve the hEGF expression significantly. The batch culture in 2.5 L fermentor showed that in-situ adsorption of acetic acid by anionic exchange resin could enhance the expression level of interested protein and reduce the fermentation period by 2 hours. And up to 10% improvement of hEGF (human epidermal growth factor)volumetric productivity (225.0 mg·L -1 ) could be achieved by supplementing 3.3 g resin per 100 ml medium.展开更多
文摘The purified D-hydantoinase was immobilized on EAH sepharose 4B via the carbodiimide method with a yield of enzyme activity up to 79.44%.The immobilized hydantoinase showed remarkable stability at 4℃.An integrated process of N-carbamoyl-D-phenylalanine(N-D-Phe)synthesis from D,L-5-benzylhydantoin(D,L-BH)catalyzed by immobilized D-hydantoinase coupled with an ion-exchange unit for in situ product removal(ISPR)was established.The variation of pH and conversion in the fixed-bed reactor with or without ISPR was compared at different temperatures,initial substrate concentrations and volumes of adsorbent.Within 24 h,the pH value in the reactor with ISPR could be kept at the alkaline range,which was beneficial to the enzymatic conversion and racemization of L-5-benzyl hydantoinase.This led to a higher overall conversion of 62.725% under optimal operation conditions,an increase of 89.3% compared with the fixed-bed reactor without ISPR.
文摘Production and accumulation of toxic by-products such as acetic acid can inhibit the growth of recombinant cells and the expression of exogenous gene in E.coli. An anionic exchange resin, A-D 3-1, which is high in adsorption selectivity and capability for acetic acid, was screened from a variety of resins based on its physical and chemical properties.On the scale of shake flask culture, the addition of 1.0 g resin per 30 ml medium was insignificant for the cell growth, however,it could improve the hEGF expression significantly. The batch culture in 2.5 L fermentor showed that in-situ adsorption of acetic acid by anionic exchange resin could enhance the expression level of interested protein and reduce the fermentation period by 2 hours. And up to 10% improvement of hEGF (human epidermal growth factor)volumetric productivity (225.0 mg·L -1 ) could be achieved by supplementing 3.3 g resin per 100 ml medium.
