An amino acid often involved in forming interchain bounds is

Options

A. Ala
B. Cys
C. Asp
D. Met.

Answer

To solve the question "An amino acid often involved in forming interchain bonds is," we will follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**:
- The question asks for an amino acid that is involved in forming interchain bonds, which are important in the structure of proteins.

2. **Identify Types of Bonds**:
- Interchain bonds in proteins are often referred to as disulfide bonds or linkages. These bonds help stabilize the secondary and tertiary structures of proteins.

3. **Know the Amino Acids**:
- Among the 20 standard amino acids, some contain sulfur, which is necessary for forming disulfide bonds. The two main sulfur-containing amino acids are cysteine and methionine.

4. **Determine Which Amino Acid Forms Disulfide Bonds**:
- Cysteine is the amino acid that can form disulfide bonds (disulfide linkages) between its thiol (-SH) groups. Methionine, while it contains sulfur, does not form disulfide bonds.

5. **Evaluate the Options**:
- The options given are:
- Alanine: Not sulfur-containing, cannot form disulfide bonds.
- Cysteine: Correct, can form disulfide bonds.
- Aspartic acid: Not sulfur-containing, cannot form disulfide bonds.
- Methionine: Sulfur-containing but does not form disulfide bonds.

6. **Select the Correct Answer**:
- Based on the analysis, the correct answer is **Cysteine**.

### Final Answer:
Cysteine is the amino acid often involved in forming interchain bonds.

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