The protein nature of enzyme was first established by

Options

A. Edward Buchner
B. Louis Pasteur
C. John Northrop
D. James Sumner

Answer

To answer the question "The protein nature of enzyme was first established by," we will go through the options provided and identify the correct scientist.

### Step 1: Understand the question
The question asks us to identify the scientist who first established that enzymes are proteins. Enzymes are biological catalysts that speed up biochemical reactions, and it is important to know their composition.

### Step 2: Analyze the options
The options given are:
1. Edward Vachner
2. Louis Pasteur
3. John Northrop
4. James Sumner

### Step 3: Evaluate each option
- **Edward Vachner**: There is no significant contribution related to enzymes attributed to him.
- **Louis Pasteur**: He is known for his work in microbiology and the process of pasteurization, but not for establishing the protein nature of enzymes.
- **John Northrop**: He is credited with demonstrating that enzymes are proteins. His work in the early 20th century was pivotal in establishing the protein nature of enzymes.
- **James Sumner**: He also worked on enzymes and was awarded a Nobel Prize, but he came after John Northrop and did not establish the protein nature first.

### Step 4: Conclusion
Based on the evaluation, the correct answer is **John Northrop**. He was the first to establish that enzymes are proteins.

### Final Answer:
The protein nature of enzyme was first established by **John Northrop**.

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