Non-competitive inhibitor

Non-competitive inhibitors are a type of enzyme inhibitors that bind to a site on the enzyme other than the active site, causing a change in the enzyme's shape and decreasing its activity. In this case, compound X is referred to as a non-competitive inhibitor because it occupies a site on the enzyme exactly opposite to that of the active site, resulting in a change in shape of the active site.

Explanation:

To understand the concept of non-competitive inhibition, we need to first understand the basic functioning of enzymes. Enzymes are biological catalysts that speed up chemical reactions by binding to specific substrates at their active site. The active site is a region on the enzyme where the substrate binds and undergoes a chemical reaction.

In the case described, a certain compound X occupies a site on the enzyme that is exactly opposite to the active site. This means that compound X is not competing with the substrate for binding at the active site, but rather binding to a different site on the enzyme.

When compound X binds to this site, it causes a change in the shape of the enzyme's active site. This change in shape prevents the substrate from binding effectively to the active site, thereby decreasing the enzyme's activity. As a result, the catalytic function of the enzyme is inhibited, and the rate of the reaction is reduced.

Comparison to competitive inhibition:

In contrast to competitive inhibition, where the inhibitor competes with the substrate for binding at the active site, non-competitive inhibition does not involve competition between the inhibitor and the substrate. Instead, the non-competitive inhibitor binds to a different site on the enzyme, causing a change in the enzyme's shape that affects the active site's functionality.

In competitive inhibition, increasing the concentration of the substrate can overcome the inhibitory effect because it increases the chances of substrate binding to the active site, outcompeting the inhibitor. However, in non-competitive inhibition, increasing the substrate concentration will not reverse the inhibitory effect because the inhibitor is not competing for the active site.

Conclusion:

In summary, when a compound occupies a site on an enzyme exactly opposite to the active site, causing a change in the shape of the active site, it is referred to as a non-competitive inhibitor. Non-competitive inhibition is a type of enzyme regulation that does not involve competition with the substrate at the active site.