An Experiment Is Performed in Which the Kinetics of an Enzyme-Catalyzed

Multiple Choice

An experiment is performed in which the kinetics of an enzyme-catalyzed reaction at different pHs is monitored.It is found that the K_m does not change but that the k_cat increases as the pH goes above 7.Which of the following is true?

A) A chemical group within the enzyme that has a pKa of around 7 is likely involved in the catalytic mechanism.
B) A chemical group with a pKa of around 7 must be deprotonated in order for substrate to bind.
C) A chemical group with a pKa of around 7 must be positively charged in order for the substrate to bind.
D) Protons are acting as positive heterotropic allosteric effectors of this enzyme.