Identify the ascending sequence of the classes of the following enzymes as per the IUB system
I) Arginosuccinase
II) Nitrate reductase
III) Pepsin
IV) Hexokinase

Options

A. II , IV , I and III
B. IV , I , III and II
C. II , IV , III and I
D. III , I , IV and II

Answer

To identify the ascending sequence of the classes of the enzymes Arginosuccinase, Nitrate reductase, Pepsin, and Hexokinase according to the International Union of Biochemistry (IUB) system, we need to classify each enzyme based on its function.

### Step-by-Step Solution:

1. **Understand the IUB Classification**: The IUB system classifies enzymes into six main classes:
- **Oxidoreductases**: Enzymes that catalyze oxidation-reduction reactions.
- **Transferases**: Enzymes that transfer functional groups from one molecule to another.
- **Hydrolases**: Enzymes that catalyze hydrolysis reactions.
- **Lyases**: Enzymes that catalyze the addition or removal of groups to form double bonds.
- **Isomerases**: Enzymes that catalyze the rearrangement of atoms within a molecule.
- **Ligases**: Enzymes that catalyze the joining of two molecules with the use of ATP.

2. **Classify Each Enzyme**:
- **Nitrate Reductase**: This enzyme is classified as an **oxidoreductase** because it catalyzes the reduction of nitrate to nitrite.
- **Hexokinase**: This enzyme is classified as a **transferase** because it transfers a phosphate group from ATP to glucose.
- **Pepsin**: This enzyme is classified as a **hydrolase** because it breaks down proteins into peptides by hydrolysis.
- **Arginosuccinase**: This enzyme is classified as a **lyase** because it catalyzes the cleavage of argininosuccinate into arginine and fumarate.

3. **Arrange the Classes in Ascending Order**:
- Based on the classifications:
- Nitrate Reductase (Oxidoreductase) - Class 1
- Hexokinase (Transferase) - Class 2
- Pepsin (Hydrolase) - Class 3
- Arginosuccinase (Lyase) - Class 4
- The ascending order of classes is:
- 1 (Oxidoreductase) → 2 (Transferase) → 3 (Hydrolase) → 4 (Lyase)

4. **Final Sequence**:
- Therefore, the ascending sequence of the classes of the enzymes is:
- Nitrate Reductase (1) → Hexokinase (2) → Pepsin (3) → Arginosuccinase (4)

### Conclusion:
The correct answer is that the ascending sequence of the classes of the enzymes is:
- Nitrate Reductase (1), Hexokinase (2), Pepsin (3), Arginosuccinase (4).