Sulphur is not a constituent of

Options

A. Cysteine
B. Ferredoxin
C. Pyridoxine
D. Methionine

Answer

To determine which option does not contain sulfur as a constituent, we will analyze each of the given options: cysteine, ferredoxin, pyridoxine, and methionine.

### Step-by-Step Solution:

1. **Understand the Role of Sulfur**:
- Sulfur is an essential mineral element required by plants and is a major constituent of certain amino acids and vitamins.

2. **Analyze Each Option**:
- **Cysteine**:
- Cysteine is an amino acid that contains sulfur in its structure. Therefore, sulfur is a constituent of cysteine.
- **Ferredoxin**:
- Ferredoxin is a protein that contains both iron and sulfur. It plays a role in electron transfer in various metabolic processes. Thus, sulfur is also a constituent of ferredoxin.
- **Methionine**:
- Methionine is another amino acid that contains sulfur. Hence, sulfur is a constituent of methionine as well.
- **Pyridoxine**:
- Pyridoxine, also known as vitamin B6, does not contain sulfur in its chemical structure. Therefore, sulfur is not a constituent of pyridoxine.

3. **Conclusion**:
- After analyzing all the options, we conclude that the correct answer is **pyridoxine** because it does not contain sulfur.

### Final Answer:
Sulfur is not a constituent of **pyridoxine**.