Phosphofructokinase I (PFK I) catalyzes the committed step in
glycolysis, which is the conversion of F 6-P to F 1,6-BP. PFK I is
also allosterically inhibited by ATP.
a. Since ATP is an end product of the pathway and is not the direct product of PFK-1, what term describes the inhibition of PFK I by ATP?
b. Why, biochemically speaking, is ATP an appropriate inhibitor of PFK I? (Again, consider the purpose of glycolysis and the significance of the PFK I reaction within glycolysis)
Ans-a- this type of inhibition is known as feedback inhibition (is allosteric inhibition) and the ATP here is negative regulator of the PFK-1 and known as allosteric inhibitor.
Ans-b- the main purpose of glycolysis is to produce ATP when cells need it. But if the production of ATP exceeded the demand for ATP it could be stressful for the cells. Since there is enough of ATP available to the cells there is no need to make more ATP. Hence the very first regulatory step of the pathway is inhibited by the end product, this direct the glucose for glycogen synthesis.
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