Who proposed the lock and key hypothesis to explain the mechanism of enzyme action and in which year?

Explanation

To answer the question regarding who proposed the lock and key hypothesis and in which year, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Hypothesis**: The question asks about the "lock and key hypothesis," which is a model that explains how enzymes interact with substrates.

2. **Determine the Proposer**: The lock and key hypothesis was proposed by a scientist. In this case, the scientist is Emil Fischer.

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