Specific activity of an enzyme refers to
A) the ratio of units of enzyme activity (initial rate in the presence of excess substrate) to the weight of protein in a given preparation.
B) the catalytic activity of an enzyme under Vmax conditions.
C) the amount of enzyme transforming 1 mole of substrate per second under standard conditions.
D) the ratio of the activity of an enzyme in an unknown sample to that of a standard or known sample under identical conditions.
E) the activity of an enzyme under specific conditions of first-order kinetics.

Question

Quizplus · Accepted Answer

Specific activity of an enzyme is defined as the ratio of units of enzyme activity (initial rate in the presence of excess substrate) to the weight of protein in a given preparation. It is used as an indicator of enzyme purity and is a measure of the enzyme's catalytic efficiency. Vmax, amount of enzyme transforming substrate per second under standard conditions, and first-order kinetics are not directly related to specific activity. D could be a measure of relative activity, but it is not the definition of specific activity.

Specific Activity of an Enzyme Refers to