Select the incorrect statement regarding enzyme ?

Options

A. Helical structure (secondary structure) of enzyme contains active site
B. Catalytic activity of an enzyme is inversely proportional to km constant.
C. Catalytic structure of most of the enzymes are tertiary and globular
D. Active site of an enzyme is a crevice in which substrate fits

Answer

To solve the question, "Select the incorrect statement regarding enzymes," we will analyze each statement provided in the question.

### Step-by-Step Solution:

1. **Identify the Statements**: We need to evaluate the statements provided regarding enzymes to find the incorrect one.

2. **Evaluate Statement 1**:
- The statement claims that the helical structure (which refers to the alpha-helix) that is the secondary structure of the enzyme contains the active site.
- This statement is incorrect because the active site of an enzyme is typically part of its tertiary structure, not its secondary structure. The secondary structure refers to local folding patterns like alpha-helices and beta-sheets, while the tertiary structure refers to the overall 3D shape of the enzyme.

3. **Evaluate Statement 2**:
- This statement suggests that the catalytic activity of the enzyme is inversely proportional to the Km constant.
- This statement is correct. The Km (Michaelis-Menten constant) indicates the substrate concentration at which the reaction rate is half of Vmax. A higher Km indicates a lower affinity of the enzyme for the substrate, which means lower catalytic activity.

4. **Evaluate Statement 3**:
- The statement mentions that the catalytic structure of most enzymes is tertiary and globular.
- This statement is also correct. Most enzymes have a tertiary structure that is globular in shape, which is essential for their function.

5. **Evaluate Statement 4**:
- This statement describes the active site of the enzyme as a crevice where the substrate fits.
- This statement is correct. The active site is indeed a specific region on the enzyme where the substrate binds and undergoes a chemical reaction.

6. **Conclusion**:
- After evaluating all statements, we find that the first statement is the only incorrect one. Therefore, the answer to the question is **Statement 1**.

### Final Answer:
The incorrect statement regarding enzymes is: **"The helical structure that is secondary structure of the enzyme contains the active site."**

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