`overset(C)overset(|)Aunderset(D)underset(|)BtoA=B+C-D`
In this reaction which of the following enzyme class should be involved ?

Options

A. Isomerases
B. Hydrolases
C. Lyases
D. Oxidoreductase

Answer

To determine which class of enzymes is involved in the reaction \( A + B + C - D \rightarrow A + B + C - D \), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reaction Type**:
The given reaction involves the transformation of compounds where groups C and D are being added or removed from the main structure (A and B).

2. **Understand Enzyme Classification**:
According to the International Union of Biochemistry (IUB) classification from 1961, enzymes are categorized into six main classes based on the type of reaction they catalyze.

3. **Analyze the Classes**:
- **Class I - Oxidoreductases**: These enzymes catalyze redox reactions (oxidation and reduction).
- **Class II - Transferases**: These enzymes transfer functional groups from one molecule to another.
- **Class III - Hydrolases**: These enzymes catalyze the hydrolysis of various bonds.
- **Class IV - Lyases**: These enzymes catalyze the addition or removal of groups to form double bonds, without affecting the double bonds themselves.
- **Class V - Isomerases**: These enzymes convert molecules into their isomers.
- **Class VI - Ligases**: These enzymes catalyze the joining of two molecules with the use of ATP.

4. **Determine the Relevant Class**:
In the reaction, groups C and D are being removed, leading to the formation of a new compound while maintaining the double bond between A and B. This indicates that the reaction involves the breaking of bonds without affecting the double bond, which is characteristic of lyases.

5. **Conclusion**:
Therefore, the enzyme class involved in this reaction is **Lyases (Class IV)**.

### Final Answer:
The enzyme class involved in the reaction \( A + B + C - D \rightarrow A + B + C - D \) is **Lyases (Class IV)**.

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