First step of an enzyme - catalyzed reaction is

Options

A. Enzyme breaks the chemical bond of substrate
B. Enzyme releases the products of the reaction
C. The substrate binds to the active site of the enzyme , fitting into the active site
D. Active site reacts with substrate forming enzyme product complex

Answer

**Step-by-Step Solution:**

1. **Understanding Enzyme-Catalyzed Reactions:**
- Enzymes are biological catalysts that speed up chemical reactions in living organisms. They work by lowering the activation energy required for a reaction to occur.

2. **Identifying the Components:**
- In an enzyme-catalyzed reaction, we have two main components: the enzyme and the substrate. The enzyme has a specific region known as the active site.

3. **First Step in the Reaction:**
- The first step of an enzyme-catalyzed reaction involves the substrate binding to the active site of the enzyme. This forms an enzyme-substrate complex.

4. **Process of Binding:**
- The substrate fits into the active site of the enzyme, much like a key fits into a lock. This specific interaction is crucial for the enzyme's activity.

5. **Conclusion:**
- Therefore, the first step of an enzyme-catalyzed reaction is the binding of the substrate to the active site of the enzyme.

**Final Answer:**
The first step of an enzyme-catalyzed reaction is the binding of the substrate to the active site of the enzyme.

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