Which of the following is not a classification of proteins

Options

A. Enzymes
B. Antibodies
C. Antigens
D. Hormones

Explanation

To solve the question "Which of the following is not a classification of proteins?", we need to analyze the given options and determine which one does not fit into the classification of proteins.

### Step-by-Step Solution:

1. **Understand the Classifications of Proteins**:
Proteins can be classified into several categories based on their functions. Common classifications include:
- Enzymes
- Antibodies
- Hormonal proteins
- Structural proteins
- Transport proteins
- Storage proteins
- Contractile proteins

2. **Examine the Options**:
The options provided are:
- A) Enzymes
- B) Antibodies
- C) Antigens
- D) Hormones

3. **Identify Each Option**:
- **Enzymes**: These are proteins that act as catalysts in biochemical reactions.
- **Antibodies**: These are proteins produced by the immune system to identify and neutralize foreign objects like bacteria and viruses.
- **Antigens**: These are not proteins; they are substances that induce an immune response, often found on the surface of pathogens. They can be polysaccharides or proteins but are not classified as proteins themselves.
- **Hormones**: Some hormones are proteins (like insulin), and they play a role in signaling and regulation in the body.

4. **Determine the Correct Answer**:
Since antigens are not classified as proteins but rather as substances that can trigger an immune response, the correct answer to the question is **C) Antigens**.

### Final Answer:
C) Antigens