One of the following is not an enzyme of digestive system

Options

A. Trypsin
B. Amylase
C. Enterogastrone
D. Enterokinase

Answer

To determine which of the following is not an enzyme of the digestive system, we need to analyze each option provided:

1. **Trypsin**: This is a digestive enzyme that breaks down proteins into smaller peptides. It is produced in the pancreas and is active in the small intestine.

2. **Amylase**: This enzyme is responsible for breaking down carbohydrates, specifically starches, into sugars. It is found in saliva (salivary amylase) and is also produced by the pancreas (pancreatic amylase).

3. **Enterokinase**: This is an enzyme that activates trypsinogen (the inactive form of trypsin) into active trypsin. It is secreted by the intestinal mucosa.

4. **Enterogastron**: This is not an enzyme; rather, it is a hormone that is secreted by the mucosa of the duodenum in response to fatty foods and other nutrients. It plays a role in inhibiting gastric movements and regulating digestive processes.

Based on the analysis, the correct answer is **Enterogastron**, as it is a hormone and not an enzyme.

### Step-by-Step Solution:
1. **Identify the options**: The options given are trypsin, amylase, enterokinase, and enterogastron.
2. **Define each term**:
- Trypsin: A protein-digesting enzyme.
- Amylase: A carbohydrate-digesting enzyme.
- Enterokinase: An enzyme that activates trypsinogen.
- Enterogastron: A hormone that regulates gastric movements.
3. **Determine which is not an enzyme**: Compare each option to see which one does not fit the category of enzymes.
4. **Conclusion**: Enterogastron is identified as the non-enzyme option.