A velocity curve (V vs.[S]) for a typical allosteric enzyme will be
A) a rectangular hyperbola.
B) a sigmoid curve.
C) a straight line.
D) a parabola.

Question

Quizplus · Accepted Answer

The sigmoid curve is characteristic of allosteric enzymes and indicates cooperativity in the binding of substrate molecules to the enzyme. As the concentration of substrate molecules increases, the enzyme becomes progressively more active, resulting in an increase in velocity that starts off slow, then accelerates rapidly, and finally levels off at a maximum velocity as the enzyme becomes saturated with substrate. This behavior is different from that of a simple enzyme, which would exhibit a rectangular hyperbola (Michaelis-Menten kinetics) with a linear increase in velocity as substrate concentration increases.

A Velocity Curve (V Vs