First, scientist to find out protein nature of enzyme was

Options

A. Kuhne
B. Buchner
C. Sumner
D. Altman et al

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the name of the first scientist who discovered that enzymes are proteins.

2. **Identifying the Options**: The options provided are Kuhne, Bushner, Sumner, and Alteman et al.

3. **Researching Historical Contributions**: Among the options, we need to identify which scientist is known for their work related to the protein nature of enzymes.

4. **Identifying James P. Sumner**: James P. Sumner is recognized for his significant contribution to biochemistry, particularly in the study of enzymes.

5. **Sumner’s Experiment**: He worked specifically with the enzyme urease, which he isolated from jack beans (JAKB).

6. **Crystallization Method**: Sumner developed a general crystallization method for enzymes. He mixed purified urease with acetone and chilled the solution, leading to the crystallization of urease.

7. **Chemical Tests**: He conducted chemical tests on the crystallized urease, which confirmed that it was indeed a protein.

8. **Conclusion**: Sumner’s work provided the first experimental proof that enzymes are proteins, making him the first scientist to discover the protein nature of enzymes.

9. **Final Answer**: Therefore, the answer to the question is James P. Sumner.

---