Give one significant contribution of Sanger

Explanation

**Step-by-Step Text Solution:**

1. **Identify the Individual**: The question asks for a significant contribution of Sanger. The person referred to is Frederick Sanger, an English biochemist.

2. **Recognize His Achievements**: Frederick Sanger is notable for being awarded the Nobel Prize twice, which highlights his significant contributions to biochemistry.

3. **First Contribution**: His first major contribution was the discovery of the structure of insulin. This work was groundbreaking in understanding how insulin functions in the body.

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