試題詳解

32. Which of the following statements about the reactions involved in amino acid metabolism is       false      ?
(A) The activity of glutamine synthetase is regulated both allosterically and by covalent modification. Adenylation of glutamine synthetase stimulates its activity.
(B) D-amino acid oxidase is present in humans, and participates in the pathways of glycine degradation.
(C) The reaction of the combination of ammonia with glutamate to form glutamine is catalyzed by glutamine synthetase. ATP is required and γ-glutamyl phosphate is an intermediate in the reaction.
(D) generated in liver mitochondria is immediately used, together with CO₂ (as ), to form carbamoyl phosphate. This ATP-dependent reaction is catalyzed by carbamoyl phosphate synthetase I.
(E) Alanine can play the role to transport ammonia from skeletal muscles to the liver. In muscles, glutamate can transfer its α-amino group to pyruvate to form alanine by alanine aminotransferase.