Which of the following forms part of a coenzyme?

Options

A. Vitamin `B_2
B. `Zn^(+2)`
C. Lipase
D. Glycine

Explanation

To determine which of the following forms part of a coenzyme, we need to analyze each option: vitamin B12, zinc, lipase, and glycine.

### Step-by-Step Solution:

1. **Understanding Coenzymes**:
- Coenzymes are small organic molecules that assist enzymes in catalyzing biochemical reactions. They are non-protein components that bind to the enzyme (apoenzyme) to form a functional enzyme (holoenzyme).

2. **Evaluating the Options**:
- **Vitamin B12**: This is a vitamin that acts as a coenzyme in various biochemical reactions, particularly in the metabolism of certain amino acids and fatty acids. It is essential for the proper functioning of enzymes.
- **Zinc**: This is a mineral and not an organic molecule. While it is a cofactor for some enzymes, it is not classified as a coenzyme.
- **Lipase**: This is an enzyme that helps in the digestion of lipids. It is not a coenzyme but rather an enzyme itself.
- **Glycine**: This is an amino acid, which is a building block of proteins, and does not function as a coenzyme.

3. **Conclusion**:
- Among the options provided, **vitamin B12** is the only one that forms part of a coenzyme.

### Final Answer:
**Vitamin B12** forms part of a coenzyme.

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