Which of the following is an example of a protein with quaternary structure?

• A. Myoglobin
• B. Hemoglobin
• C. Insulin
• D. Lysozyme

Answer: (B)

Verified step by step guidance

1. Understand the concept of protein structure: Proteins have four levels of structure - primary, secondary, tertiary, and quaternary. Quaternary structure refers to the assembly of multiple polypeptide chains into a functional protein complex.
2. Identify the characteristics of quaternary structure: Proteins with quaternary structure consist of two or more polypeptide chains, also known as subunits, that come together to form a functional protein.
3. Analyze the given options: Myoglobin, Hemoglobin, Insulin, and Lysozyme. Determine which of these proteins are known to have multiple polypeptide chains.
4. Recall that Myoglobin is a single polypeptide chain and does not have a quaternary structure. Insulin is composed of two chains but is not typically considered to have a quaternary structure in the same way as larger complexes. Lysozyme is a single polypeptide chain.
5. Recognize that Hemoglobin is composed of four polypeptide subunits, making it a classic example of a protein with quaternary structure. Therefore, Hemoglobin is the correct answer.