The b-pleated sheet structure of proteins is due to

Options

A. formation of peptide bonds
B. coiling of polypeptide chains
C. folding of the coiled polypeptide chains
D. linking together of two or more polypeptide chains.

Answer

### Step-by-Step Solution:

1. **Understanding the Beta-Pleated Sheet Structure**:
- The beta-pleated sheet is a type of secondary structure found in proteins. It consists of polypeptide chains that are arranged side by side, forming a sheet-like structure.

2. **Formation of Peptide Bonds**:
- Peptide bonds are formed between amino acids to create polypeptide chains. However, while peptide bonds are essential for forming the primary structure of proteins, they do not directly lead to the formation of the beta-pleated sheet structure.

3. **Coiling of Polypeptide Chains**:
- Polypeptide chains can coil to form alpha helices, another type of secondary structure. However, this coiling does not contribute to the formation of beta-pleated sheets.

4. **Folding of Coiled Polypeptide Chains**:
- While folding is a general characteristic of protein structure, it does not specifically describe how beta-pleated sheets are formed.

5. **Linking Together of Two or More Polypeptide Chains**:
- The beta-pleated sheet structure is formed by the linking of two or more polypeptide chains through hydrogen bonds. These chains can be arranged in parallel or anti-parallel configurations, contributing to the stability and structure of the beta-pleated sheet.

6. **Conclusion**:
- Therefore, the correct answer to the question is that the beta-pleated sheet structure of proteins is due to the linking together of two or more polypeptide chains.

### Final Answer:
The beta-pleated sheet structure of proteins is due to the linking together of two or more polypeptide chains.

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