The ___enzyme was first discovered in E.coli

Options

A. DNA Polymerase
B. Primase
C. Topoisomerase
D. Helicase

Answer

To solve the question "The ___ enzyme was first discovered in E. coli," we need to identify which enzyme among the given options was the first to be discovered in E. coli.

### Step-by-Step Solution:

1. **Identify the Options**: The options provided are:
- 1st: DNA polymerase
- 2nd: Primase
- 3rd: Topoisomerase
- 4th: Helicase

2. **Evaluate DNA Polymerase**:
- DNA polymerase is a crucial enzyme involved in DNA replication.
- While it is found in E. coli, it was not the first enzyme discovered in this bacterium.
- **Conclusion**: This option is incorrect.

3. **Evaluate Primase**:
- Primase is also involved in DNA replication, synthesizing RNA primers needed for DNA synthesis.
- Although it is associated with bacterial DNA replication, it was not the first enzyme discovered in E. coli.
- **Conclusion**: This option is incorrect.

4. **Evaluate Topoisomerase**:
- Topoisomerase is known for its role in managing DNA supercoiling during replication.
- It was first discovered in E. coli by scientist James Wang in 1971.
- This makes it a strong candidate for the enzyme that was first discovered in E. coli.
- **Conclusion**: This option is correct.

5. **Evaluate Helicase**:
- Helicase is responsible for unwinding the DNA double helix during replication.
- While it is present in various organisms, including viruses, it was not the first enzyme discovered in E. coli.
- **Conclusion**: This option is incorrect.

### Final Answer:
The correct answer is **Topoisomerase**.

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