What are the products of the reaction catalyzed by arginosuccinate synthetase in the urea cycle?

The reaction catalyzed by arginosuccinate synthetase is crucial in the urea cycle, a biochemical pathway that converts ammonia to urea for excretion. This enzyme facilitates the condensation of citrulline and aspartate, leading to the formation of argininosuccinate.

During this reaction, citrulline, which is produced from ornithine, combines with aspartate to create argininosuccinate, an intermediate in the cycle. The reaction is an example of a synthetase reaction, requiring ATP to activate the carboxyl group of aspartate, enabling its incorporation into the growing molecule.

After the formation of argininosuccinate, further reactions in the urea cycle will eventually lead to the production of arginine and release fumarate. However, argininosuccinate synthetase specifically produces citrulline and argininosuccinate as the direct products of its enzymatic activity. Therefore, the correct choice accurately reflects the immediate outcome of this enzymatic reaction in the urea cycle, confirming the key role of arginosuccinate synthetase in nitrogen metabolism.