Question

Describe transition state theory and how it applies to enzyme catalysis. Why is a transition-state analog not necessarily the same as a competitive inhibitor?

Answer 1

The transition state theory helps to explain the reaction rates of various chemical reacions.According to this theory,enzymatic catalysis that occurs is equivalent and more when enzyme binds to the transition state than when it binds to the reactants in the ground state.This theory takes into account an chemical equilibrium known as quasi-equilibrium between reactants and activated transition state complexes.

The transition -state analog is similar in structure to the transition-state structure of the enzyme-substrate complex wheras the structure of a competitive inhibitor might be similar to the structure of the substrate itself. As the competitive inhibitor has similar structure of the substrate,it means that it will compete with the substrate for the active site of the enzyme and will succeed in binding at the active site of the enzyme thereby blocking the normal substrate from binding to the enzyme and increasing the substrate concentration will help overcome the competitive inhibition but in case of transition state analog,which is similar in structure to the transition-state enzyme substrate complex ,the analog binds tightly to the enzyme and increasing the substrate concentration will not be able to overcome the transition analog from binding the enzyme.