Detoxification of ammonia by immobilized urea cycle enzymes.

Detoxication of ammonia was performed by dialysis of ammonia through a hollow fiber unit and by conversion to urea in a column reactor packed with immobilized urea cycle enzymes. Enzymes in the urea cycle could be immobilized by covalently binding on CNBr-activated Sepharose 4B. Ammonia was sequentially converted to urea by immobilized urea cycle enzymes with an ATP-regenerating system. Optimum conditions for the cyclic reaction were obtained theoretically and experimentally for performing continuous urea synthesis in a packed column reactor. Detoxication of ammonia of similar concentration to that in the blood in hepatic insufficiency was analyzed and performed experimentally in an extracorporeal model.