Some drug do not bind to the enzyme's active site , instead bind to a different site of enzyme . This site is called.

Options

A. allosteric site
B. substrate site
C. ionic site
D. competitve site .

Answer

To solve the question, we need to identify the site on an enzyme where some drugs bind, which is different from the active site. Here’s a step-by-step breakdown of the solution:

### Step-by-Step Solution:

1. **Understanding Enzymes**: Enzymes are biological catalysts that speed up biochemical reactions in living organisms. They have specific regions where substrates bind to facilitate these reactions.

**Hint**: Recall that enzymes have specific structures that allow them to interact with substrates.

2. **Identifying the Active Site**: The active site is the specific region on the enzyme where the substrate binds. This site is crucial for the enzyme's catalytic activity.

**Hint**: Think about how the shape and chemical environment of the active site are tailored for substrate binding.

3. **Recognizing Other Binding Sites**: Besides the active site, enzymes can have other sites where molecules can bind. These sites can influence the enzyme's activity without directly participating in the reaction.

**Hint**: Consider how binding at different sites can affect the enzyme's function.

4. **Defining the Allosteric Site**: The site where drugs or other molecules bind that is not the active site is known as the allosteric site. Binding at this site can change the enzyme's shape and function, either enhancing or inhibiting its activity.

**Hint**: Remember that "allo" means "other," indicating that this site is different from the active site.

5. **Conclusion**: Therefore, the site on the enzyme where some drugs bind, which is different from the active site, is called the **allosteric site**.

### Final Answer:
The site is called the **allosteric site**.