Which among the following is a peptide linkage ?

Options

A.
B.
C.
D.

Answer

To determine which among the given options is a peptide linkage, we need to understand the structure and formation of a peptide bond.

### Step-by-Step Solution:

1. **Understanding Amino Acids**:
- Amino acids are the building blocks of proteins. Each amino acid has a basic structure consisting of an amino group (-NH2), a carboxyl group (-COOH), and a variable side chain (R group).

2. **Formation of Peptide Linkage**:
- A peptide bond is formed when two amino acids undergo a condensation reaction. This occurs between the amino group of one amino acid and the carboxyl group of another.

3. **Elimination of Water**:
- During the formation of the peptide bond, a molecule of water (H2O) is eliminated. The reaction can be represented as:
\[ \text{Amino Acid 1} + \text{Amino Acid 2} \rightarrow \text{Dipeptide} + H2O \]

4. **Structure of Peptide Bond**:
- The resulting bond between the carbon atom of the carboxyl group of one amino acid and the nitrogen atom of the amino group of another amino acid is called a peptide bond. The structure can be represented as:
\[ -C(=O)-NH- \]
- This can be seen as a carbonyl group (C=O) bonded to a nitrogen atom (NH).

5. **Identifying Peptide Linkage**:
- To identify a peptide linkage among the options provided, look for the structure that resembles the peptide bond described above, specifically the -C(=O)-NH- linkage.

### Conclusion:
- The correct option that represents a peptide linkage will have the structure of -C(=O)-NH-.