What is common among amylase, rennin and trypsin?

Options

A. All are proteins
B. Proteolytic enzyme
C. Produced in stomach
D. Act at pH lower than 7

Explanation

To answer the question "What is common among amylase, rennin, and trypsin?", we can analyze the options provided in the video transcript step by step.

### Step-by-Step Solution:

1. **Identify the Nature of the Enzymes**:
- Amylase, rennin, and trypsin are all enzymes that facilitate biochemical reactions in the body.
- Specifically, they are all proteins, as enzymes are biological catalysts that are typically made up of amino acids.

2. **Evaluate Each Option**:
- **Option 1: All are proteins**:
- This is true. All three enzymes are proteins, which is a common characteristic.
- **Option 2: All are proteolytic enzymes**:
- This is incorrect because only rennin and trypsin are proteolytic enzymes (they break down proteins). Amylase breaks down starch, not proteins.
- **Option 3: All are produced in the stomach**:
- This is incorrect. Rennin is produced in the stomach, but amylase and trypsin are produced in the pancreas.
- **Option 4: All act at a pH lower than 7**:
- This is incorrect. While amylase and rennin have optimum pH levels below 7, trypsin has an optimum pH of around 8, which is above 7.

3. **Conclusion**:
- The commonality among amylase, rennin, and trypsin is that **all three are proteins**.

### Final Answer:
The common characteristic among amylase, rennin, and trypsin is that **all are proteins**.