Question 14 of 16

The answer you chose is highlighted in reverse video. The correct answer is in bold.

Major controls of de novo AMP synthesis include:

1. allosteric inhibition by GMP.
2. allosteric inhibition by AMP.
3. availability of PRPP.
4. stimulation by GTP..

A. 1, 2 and 3
B. 1 and 3
C. 2 and 4
D. 4 only
E. All four

The correct answer is (E).

Comments:

1 and 2. Both of these are inhibitors of gln-PRPP amidotransferase and their effect is synergistic.
3. Since the kinetics of gln-PRPP amidotransferase are sygmoidal with respect to PRPP, and the concentrations are in the steep part of the curve, [PRPP] can significantly influence the rate.
4. GTP provides the energy for the branch from IMP to AMP.

Return to Question Document

cna

Last modified 1/5/95