Some drugs bind to a site other than the active site of an enzyme. This site is known as

Solution

Chemistry ma’am · 4 steps

Allo means other: a drug that sits on some other site of the enzyme is using its allosteric site.

1. Two ways to block. An enzyme inhibitor can block the active site directly, competing with the substrate for it. Or it can bind somewhere else on the enzyme.
2. The other site. That second binding site is called the allosteric site. A drug bound there changes the shape of the active site, so the substrate can no longer fit into it properly.
3. Why it matters. If the bond between the drug and the allosteric site is strong, the substrate cannot undo the change. This blocks the enzyme even when there is a lot of substrate around.
4. So. The site other than the active site where some drugs bind is the allosteric site, option (b).

The idea to keep. Competitive inhibitors fight the substrate for the active site. Allosteric inhibitors bind elsewhere and change the active site's shape. Remember: allo means other.

Answer from the NTA final answer key. Solution by PrepWiser.