Which of the following is the allosteric activator of carbamoyl phosphate synthase I?: (A) Glutamine, (B) Oxaloacetate, (C) N-acetyl aspaate, (D) N-acetyl glutamate
Answer is D. Carbamoyl phosphate synthase I is the rate-limiting enzyme of the urea cycle Active only in the presence of N-acetylglutamate(NAG), an allosteric activator that enhances the affinity of the synthase for ATP. Arginine is the allosteric activator of NAG synthase.