試題詳解

28. Which of the following conditions concerning de novo purine ribonucleotide synthesis is FALSE?
(A) Glutamate is a direct source of nitrogen atom for the purine ring.
(B) The utility of PRPP is committed step in the synthesis of phosphoribosylamine.
(C) Aspartate is a direct source of nitrogen atom for the purine ring.
(D) IMP is an intermediate in the synthesis of GMP and AMP.
(E) De novo synthesis of purine ribonucleotide would be inhibited by methotrexate.