Question

Characterization of the complete three-dimensional structure of a newly purified protein suggests that it catalyzes the breakdown of a large substrate. The protein consists of a single polypeptide chain. It has a large pocket that appears to be the binding site for the substrate and a smaller indentation that appears to be the binding site for a regulatory molecule. What do these structural observations suggest about the mechanism by which the activity of this protein is likely regulated?

Answer 1

Answer:

The options

A) It is probably an enzyme that is regulated by noncompetitive inhibition.

B) It is probably a multi-subunit enzyme that is regulated by allosteric regulation.

C) It is probably an enzyme that is regulated by competitive inhibition.

D) It is probably an enzyme that is regulated by cooperativity.

The CORRECT ANSWER IS A)

A) It is probably an enzyme that is regulated by noncompetitive inhibition.

Explanation:

This kind of protein is an enzyme that possesses a singular polypeptide chain, that is to say, it lacks more subunits. The pocket is localised in the binding site for the necessary substrate or active site, and the cavity is a binding site for a different molecule. This seperate molecule is a known to be a regulatory molecule or an inhibitor. In this case study, the inhibitor adhere itself to a different site which isn't the active site. When an inhibitor attaches itself in a site which is not the active site, it is reported that this molecule behaves in the form of a noncompetitive inhibitor.