Which of the following restriction enzymes produces blunt ends ?

Options

A. Sal I
B. Eco RV
C. Xho I
D. Hind III

Answer

To determine which of the following restriction enzymes produces blunt ends, we need to analyze each option provided: Sal-1, Eco-R5, Xho-1, and Hin-3.

### Step-by-Step Solution

1. **Understanding Restriction Enzymes**:
- Restriction enzymes are proteins that cut DNA at specific sequences. They can create two types of ends: **blunt ends** (where the cut is straight across both strands) and **sticky ends** (where the cut leaves overhanging nucleotides).

2. **Analyzing Sal-1**:
- The recognition sequence for Sal-1 is 5' GTCGAC 3' (and its complementary strand).
- When Sal-1 cuts, it creates sticky ends, not blunt ends.
- **Conclusion**: Sal-1 does not produce blunt ends.

3. **Analyzing Eco-R5**:
- The recognition sequence for Eco-R5 is 5' GATATC 3' (and its complementary strand).
- Eco-R5 cuts the DNA in such a way that it creates blunt ends, as the cut occurs at equal positions on both strands.
- **Conclusion**: Eco-R5 produces blunt ends.

4. **Analyzing Xho-1**:
- The recognition sequence for Xho-1 is 5' CTCGAG 3' (and its complementary strand).
- Xho-1 also produces sticky ends due to the nature of the cut.
- **Conclusion**: Xho-1 does not produce blunt ends.

5. **Analyzing Hin-3**:
- The recognition sequence for Hin-3 is 5' AAGCTT 3' (and its complementary strand).
- Similar to Xho-1, Hin-3 produces sticky ends.
- **Conclusion**: Hin-3 does not produce blunt ends.

6. **Final Conclusion**:
- Among the options provided, only **Eco-R5** produces blunt ends.

### Answer:
The restriction enzyme that produces blunt ends is **Eco-R5**.