Which functional group participates in the disulphide bond formation in proteins?
(a)Thiolactone
(b)Thiol
(c)Thioether
(d)Thioester

Options

A. Thiolactone
B. Thiol
C. Thioether
D. Thioester

Explanation

To determine which functional group participates in the formation of disulfide bonds in proteins, we can follow these steps:

### Step 1: Understand Disulfide Bonds
Disulfide bonds are covalent bonds that form between the sulfur atoms of two cysteine residues in proteins. This occurs through the oxidation of thiol groups.

### Step 2: Identify the Functional Groups
The options provided are:
- (a) Thiolactone
- (b) Thiol
- (c) Thioether
- (d) Thioester

### Step 3: Define Each Functional Group
- **Thiol**: Contains a sulfur atom bonded to a hydrogen atom (-SH).
- **Thiolactone**: A cyclic compound that contains a thiol group.
- **Thioether**: Contains a sulfur atom bonded to two carbon atoms (R-S-R').
- **Thioester**: Contains a sulfur atom bonded to a carbonyl group (R-C(=O)-S-R').

### Step 4: Relate to Disulfide Bond Formation
Disulfide bonds are specifically formed between two thiol groups (-SH). When two cysteine residues come close together, their thiol groups can oxidize to form a disulfide bond (S-S).

### Step 5: Conclusion
Since disulfide bonds are formed by the oxidation of thiol groups, the correct answer is:
**(b) Thiol**