Secondary protein is stable by

Options

A. Hydrogen bonding
B. peptide link
C. Glycosidic linkage
D. None of these

Answer

To solve the question regarding what stabilizes the secondary structure of proteins, we can break it down step by step.

### Step-by-Step Solution:

1. **Understanding Protein Structure**:
- Proteins have four levels of structure: primary, secondary, tertiary, and quaternary.
- The secondary structure refers to local folded structures that form within a protein due to interactions between amino acids.

2. **Types of Secondary Structures**:
- The two main types of secondary structures are:
- **Alpha Helix**: A right-handed coiled structure.
- **Beta Sheet**: A sheet-like structure formed by hydrogen bonds between strands.

3. **Role of Hydrogen Bonds**:
- The stability of both alpha helices and beta sheets is primarily due to hydrogen bonding.
- In alpha helices, hydrogen bonds form between the backbone amide hydrogen of one amino acid and the carbonyl oxygen of another amino acid four residues down the chain.
- In beta sheets, hydrogen bonds occur between the carbonyl oxygen of one strand and the amide hydrogen of another strand, stabilizing the sheet-like structure.

4. **Evaluating the Options**:
- The options provided were:
- A) Hydrogen bonding
- B) Peptide link
- C) Glycosidic linkage
- D) None of these
- Since we established that hydrogen bonds are crucial for stabilizing the secondary structure, we can conclude that option A is correct.

5. **Conclusion**:
- The secondary protein structure is stabilized by **hydrogen bonding**.

### Final Answer:
The secondary protein structure is stabilized by **hydrogen bonding**.

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