Consider the stoichiometric reaction S → P that is enzyme catalyzed and is found to follow...

Consider the stoichiometric reaction S → P that is enzyme catalyzed and is found to follow Michaelis-Menten kinetics. Its maximum velocity Vmax is equal to 100 M s-1 In the presence of a competitive inhibitor (I), the following data are obtained:

a. What is the value of the Michaelis constant KM in the absence of an inhibitor?

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b. What is the value of the dissociation constant for the enzyme-inhibitor complex KI ?

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c. The proposed mechanism for the reaction is

Assume that there is a transition state between each reactant, intermediate, and product. They are, in order, ES‡, EZ‡, and EP‡. From the following thermodynamic and kinetic data, plot energy vs. reaction coordinate. Label the position of the substrate, each intermediate, and each transition state with its energy value relative to product P, taken as the zero of energy.

Reaction	AH° (kJ mol-1)	AH* (kJ mol-1)
S s P	-30	—
E + S s ES	—	+12
ES s EP	+4	+46
EP s E + P	-25	+75

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d. Which kinetic rate coefficient would you measure as a function of temperature to obtain ΔH‡ for EP → E + P? What is the value of ΔH‡ corresponding to k-1?

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e. Which step in the reaction do you think is rate determining? Why?