An example of protein with quaternary structure is

Options

A. Myoglobin
B. Haemoglobin
C. Keratin
D. All of these

Answer

To answer the question regarding an example of a protein with quaternary structure, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Quaternary Structure**:
- The quaternary structure of a protein refers to the assembly of multiple polypeptide chains (subunits) into a single functional protein complex. This structure is characteristic of multimeric proteins.

2. **Identify Multimeric Proteins**:
- Multimeric proteins are those that consist of more than one polypeptide chain. Each polypeptide chain has its own tertiary structure but comes together to form the overall quaternary structure.

3. **Example of a Protein with Quaternary Structure**:
- One well-known example of a protein with a quaternary structure is **hemoglobin**. Hemoglobin is composed of four polypeptide chains: two alpha chains and two beta chains.

4. **Function of Hemoglobin**:
- Hemoglobin functions primarily in the transport of oxygen and carbon dioxide in the blood. The arrangement of its subunits allows it to efficiently bind and release these gases.

5. **Conclusion**:
- Therefore, the correct answer to the question is hemoglobin, as it exemplifies a protein with a quaternary structure.

### Final Answer:
**Hemoglobin** is an example of a protein with quaternary structure.

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