Question 11 of 16

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A nucleoside phosphorylase:

1. cleaves a nucleoside with the production of ribose 1-phosphate.

2. is necessary for the major salvage pathway for pyrimidines.

3. is used in the degradation of purine nucleotides.

4. is responsible for the equilibration of nucleoside monophosphates and nucleoside diphosphate.

A. 1, 2 and 3

B. 1 and 3

C. 2 and 4

D. 4 only

E. All four

The correct answer is (A).

Comments:

1. As the name implies, the reaction is a phosphorolysis.

2. The pyrimidine salvage is a two-step pathway. The next step is catalyzed by a kinase.

3. This is true for the degradation of both purine and pyrimidine nucleosides

4. This equilibration is catalyzed by nucleoside monophosphate kinases.

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Last modified 1/5/95