Regulatory sites present over the enzymes are called

Options

A. Active sites
B. Catalytic groups
C. Buttressing sites
D. Allosteric sites

Answer

**Step-by-Step Solution:**

1. **Understanding Enzymes**: Enzymes are biological catalysts that speed up chemical reactions in living organisms. They can either enhance or decrease the rate of a reaction depending on various factors.

2. **Identifying the Active Site**: The active site of an enzyme is the specific region where the substrate binds. This site is crucial for the enzyme's catalytic activity, as it is where the conversion of substrate to product occurs.

3. **Exploring Other Sites**: Besides the active site, enzymes can have other sites that influence their activity. One such site is known as the buttressing site, which helps align the substrate with the active site for better binding.

4. **Defining Allosteric Sites**: Allosteric sites are specific sites on an enzyme, separate from the active site. These sites can bind regulatory molecules, which can either enhance or inhibit the enzyme's activity.

5. **Analyzing the Options**:
- **Active Site**: This is where the substrate binds but does not regulate enzyme activity.
- **Catalytic Group**: These are components that assist in the reaction but are not regulatory sites.
- **Buttressing Sites**: These help in substrate alignment but do not regulate the enzyme.
- **Allosteric Sites**: These are the regulatory sites that can bind regulators or inhibitors to modulate enzyme activity.

6. **Conclusion**: The correct answer to the question is that the regulatory sites present over enzymes are called **allosteric sites**.

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