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.