Back in 1962, Gerhart and pardee developed a model for the regulation of the act
ID: 174710 • Letter: B
Question
Back in 1962, Gerhart and pardee developed a model for the regulation of the activity of the ATC ase by CTP and ATP, using the pathway given in figure Describe that model, using information presented here as well as what you have learned about allosteric enzymes. Be sure to include a sentence explaining the physiological significance of your model. Many years later, in 1989, wild, et al. revisited the idea of allosteric control of ATCase by CTP. They noted that CTP did indeed ATCase, but that the was always incomplete, even at high concentrations of CTP. They hypothesized that perhaps CTP did not act alone, but in combination with some other nucleotide. They tested the activity of ATCase in the presence of several nucleotideExplanation / Answer
John Gerhart and Arthur Pardee developed a model that proved that the activity of the enzyme ATCase(aspartate transcarbamoylase) could be regulated with CTP and ATP.
The model:
From figure 1, we can explain the activity of ATCase enzyme and the effect of CTP and ATP on the pyramidine synthesis as done by Gerhart and Pardee. It clearly shows that ATCase catalysed reaction is fast when the concentration of CTP is less and the reaction rate decreases as the concentration of CTP increases.
It shows a sigmaoidal behavior as the presence of more amounts of CTP inhibit the end product formation by ATCase enzyme.
physiological significance:
this inhibitory effect shows physiological significance as the structure of CTP is entirely different from that of the substrate that binds to the enzyme ATCase at the active site. This means that CTP binds to the enzyme at a different site other than the active site. This is called as allosteric nature of the enzyme. The enzyme binds to an effector (CTP) and shows a confirmation change and thus leading to the regulation of the end product formation.
here CTP acts as an allosteric inhibitor that is inhibition the reaction.
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