Select the correct statement

Options

A. Agonists are the substances which inhibit the natural function of receptor site
B. Agonists are the drugs that mimic the natural messenger by switching on the receptor
C. Substrates may bind to active site of enzyme through the variety of interactions such as ionic bonding , H - bonding , Van dar Waal's interaction or dipole - dipole interaction
D. All of these

Answer

To solve the question regarding the correct statement about agonists, let's analyze each statement step by step.

### Step 1: Understand the Definitions
- **Agonist**: A substance that binds to a receptor and activates it, mimicking the action of a natural messenger.
- **Antagonist**: A substance that binds to a receptor but does not activate it, inhibiting the natural function of the receptor.

### Step 2: Analyze Each Statement
1. **Statement 1**: "Agonists are the substances which inhibit the natural function of the receptor site."
- This statement is **false** because agonists activate receptors rather than inhibit them.

2. **Statement 2**: "Agonists are the drugs that mimic the natural messenger by switching on the receptor."
- This statement is **true** as it accurately describes the function of agonists.

3. **Statement 3**: "When the substrate binds to the active site of the enzyme, it binds through a variety of interactions."
- This statement is also **true** because substrates bind to enzymes through various interactions such as hydrogen bonds, ionic interactions, and hydrophobic effects.

### Step 3: Conclusion
- From the analysis, we conclude that **Statement 2** and **Statement 3** are correct, while **Statement 1** is incorrect.

### Final Answer
The correct statements are:
- Statement 2: True
- Statement 3: True
- Statement 1: False