Question 1 of 16

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In tissues that do not carry out active de novo synthesis, maintenance of an adequate supply of adenine nucleotides:

A. occurs primarily by adenine salvage using A-PRT.
B. requires ATP uptake from the blood.
C. depends upon the action of nucleoside phosphorylase
D. is accomplished entirely by the action of adenylate kinase.
E. involves hypoxanthine salvage using HG-PRT.

The correct answer is (E).

Comments:

A. A-PRT is not considered to be the major enzyme because we produce very little free adenine.
B. Phosphorylated compounds generally don't cross the plasma membrane.
C. This enzyme is primarily for the salvage of pyrimidines.
D. Adenylate kinase equilibrates ATP, AMP and ADP
E. Correct. The IMP formed is converted to AMP by amination with aspartate.

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Last modified 1/5/95