Abstract
The urea cycle and related enzymes were immobilized on CNBr-activated Sepharose 4B. Ammonia was succesively converted to urea by the immobilized urea cycle enzymes with ATP-regenerating systems.
The optimum conditions for the cycle reaction in a packed column reactor were obtained theoretically and experimentally for performing continuous urea synthesis under various feed concentrations of ammonia, ornithine and ATP. The optimum packed system for urea synthesis was obtained by separating carbamoylphosphate synthetase (EC 2. 7. 2. 5) from ornithine-cycled enzymes, i. e. ornithine carbamoyltransferase (EC 2. 1. 3. 3), argininosuccinate synthetase (EC 6. 3. 4. 5), argininosuccinate lyase (EC 4. 3. 2. 1) and arginase (EC 6. 5. 3. 1), mixing the ornithine-cycled enzymes in one phase. The optimal total enzyme activties required and ATP-efficiency for urea conversion from ammonia in the packed system were also obtained.
