What is the difference between allosteric and competitive inhibition?

Allosteric inhibition involves a molecule binding to a site other than the active site, while competitive inhibition involves direct competition at the active site.

Allosteric and competitive inhibition are two types of enzyme inhibition that regulate the activity of enzymes in a cell. They differ in the way they interact with the enzyme and how they affect the enzyme's function.

In allosteric inhibition, an inhibitory molecule binds to a site on the enzyme that is different from the active site. This site is known as the allosteric site. The binding of the inhibitor to the allosteric site causes a conformational change in the enzyme's structure, which alters the shape of the active site. This change in shape prevents the substrate from binding to the active site, thus inhibiting the enzyme's activity. Allosteric inhibition is a form of non-competitive inhibition, as the inhibitor does not compete with the substrate for the active site.

On the other hand, competitive inhibition involves a molecule that is similar in structure to the substrate of the enzyme. This molecule, known as the competitive inhibitor, competes with the substrate for the active site on the enzyme. If the competitive inhibitor binds to the active site, it prevents the substrate from binding, thus inhibiting the enzyme's activity. However, this inhibition can be overcome by increasing the concentration of the substrate, as the more substrate molecules there are, the less likely it is that the inhibitor will bind to the active site.

IB Biology Tutor Summary: Allosteric inhibition happens when a molecule binds to a part of the enzyme not where substrates usually bind, changing its shape and stopping it from working. Competitive inhibition occurs when a molecule competes with the substrate for the enzyme's active site. Increasing substrate concentration can overcome competitive inhibition, but not allosteric inhibition.