For an enzyme-substrate pair, a graph of reaction rate versus substrate concentration gives an S-shaped curve. From these data which of the following is the most likely conclusion?
A) The enzyme conforms closely to the Michaelis equation.
B) The enzyme contains more than one kind of polypeptide chain.
C) In high concentrations, the substrate is an inhibitor.
D) More than one binding site for the substrate is present in each enzyme unit.
E) The enzyme is subject to product inhibition.

Question

Quizplus · Accepted Answer

The S-shaped curve indicates that the enzyme has more than one binding site for the substrate, which is characteristic of enzymes with cooperativity (positive allosteric regulation). This type of behavior cannot be explained by the Michaelis-Menten equation alone and suggests that there are additional binding sites that affect the catalytic activity of the enzyme. Additionally, the presence of product inhibition or multiple polypeptide chains would not necessarily result in an S-shaped curve.

For an Enzyme-Substrate Pair, a Graph of Reaction Rate Versus