Question

A regulator binds an enzyme's active site via covalent bonds, thus inhibiting the substrate from binding. What type of regulation is this?

1) Competitive inhibition
2) Noncompetitive inhibition
3) Allosteric regulation
4) Feedback inhibition

Answer 1

The regulation described, where a regulator molecule covalently binds to an enzyme's active site, is a form of noncompetitive inhibition, usually considered as irreversible inhibition within this context.

Step-by-step explanation:

The type of enzyme regulation described in the question is noncompetitive inhibition. When a regulator molecule binds covalently to the active site and inhibits the enzyme, it is actually a form of irreversible inhibition, which is a subset of noncompetitive inhibition. Noncompetitive inhibitors typically bind to an allosteric site, causing a conformational change that affects the enzyme's active site.

However, the question specifies that the regulator binds via covalent bonds, which is often irreversible, differing from the classic reversible allosteric control. Therefore, the answer would be noncompetitive inhibition due to the absence of a competitive mechanism and the lack of specification of reversible conformational change as seen in classic allosteric regulation.