How is the catalytic proficiency defined?
A)It is the reciprocal of the turnover number.
B)It is the logarithm of the Michaelis-Menton constant.
C)It is equal to the rate constants for a reaction in the presence of the enzyme divided by the rate constant for the same reaction in the absence of the enzyme.
D)It is the rate of the enzyme-catalyzed reaction in the presences of a standard concentration of enzyme.

Question

Quizplus · Accepted Answer

Catalytic proficiency is defined as the enhancement in the rate of a reaction by an enzyme, compared to the rate of the same reaction in the absence of an enzyme. This is expressed as the ratio of the rate constant for the enzyme-catalyzed reaction (kcat) to the rate constant for the non-catalyzed (uncatalyzed) reaction (kuncat). Therefore, the correct option is C. Option A is incorrect as turnover number is defined as the number of substrate molecules converted to product per unit time by a single enzyme molecule. Option B is incorrect as the Michaelis-Menten constant is a measure of the affinity of an enzyme for its substrate. Option D is incorrect as the rate of an enzyme-catalyzed reaction is dependent on the substrate concentration, as well as the enzyme concentration.

How Is the Catalytic Proficiency Defined