e on your model noted that CTP did indeed inhibit by CTP The

e on your model. noted that CTP did indeed inhibit by CTP. They concentrations ATCase, but that the inhibition was always incomplete, even at high with of CTP. They hypothesized that perhaps CTP did not act alone, but in combination other nucleotide. They tested the activity of ATCase in the presence several nucl combinations. The results are shown of in Table 16.3. a. What combination gives the most effective inhibition? b. What is the physiological significance of this combination? c. Revise Figure 16.1 to include this new information. d. Redraw Figure 16.2 to include this new information. How does the KM ofthe nucleotide combination compare with the values for the nucleotides alone? Table 16.3: Relative specific activities for combinations of nucleotide effectors. A value greater than one indicates stimulation, a value less than one indicates inhibition. Aspartate Concentration Nucleotide Effector 5.0 mM 2.5 mM ATP 13s CTP 0.31 043 GTP 0.71 0.95 0.95 0.85 ATP/CTP 0.70 1.58 ATP/GTP ATP/UTP 0.58 0.41 CTP/GTP 0.06 CTP/UTP GTP/UTP 066 0.84

Solution

a. What combination gives the most effective inhibition?

Answer: