Protein digesting other proteins belongs to IUB class

Options

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

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the classification of enzymes that digest proteins. Specifically, it refers to the International Union of Biochemistry (IUB) classification system.

2. **Identifying the Enzyme Type**: Protein-digesting enzymes are also known as proteases or peptidases. These enzymes break down proteins into smaller peptides or amino acids.

3. **Reviewing IUB Classes**: The IUB has classified enzymes into six main classes:
- Oxidoreductases
- Transferases
- Hydrolases
- Lyases
- Isomerases
- Ligases

4. **Analyzing the Options**: The options given are:
- Oxidoreductases
- Transferases
- Hydrolases
- Isomerases

5. **Determining the Correct Class**:
- **Hydrolases**: These enzymes catalyze the breaking of bonds using water. Since protein-digesting enzymes (like pepsin) break down proteins by cleaving peptide bonds with the addition of water, they fall under this category.
- **Lyases**: While they also break bonds, they do not use water in their mechanism.
- **Oxidoreductases, Transferases, and Isomerases**: These classes do not specifically relate to the digestion of proteins.

6. **Conclusion**: Based on the classification and function of the enzymes, the correct answer is that protein-digesting enzymes belong to the IUB class of **Hydrolases**.

### Final Answer:
Protein digesting enzymes belong to the IUB class of **Hydrolases**.

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