The enzyme which does not directly act upon the food substracte in the small intestine of man, is

Options

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

Answer

To solve the question, "The enzyme which does not directly act upon the food substrate in the small intestine of man, is," we will analyze the given options step by step.

### Step-by-Step Solution:

1. **Understanding the Question**:
- We need to identify an enzyme that does not act directly on food substrates in the small intestine.

2. **Analyzing the Options**:
- **Option A: Amylase**:
- Amylase is an enzyme that breaks down carbohydrates (specifically starch) into simpler sugars (monosaccharides and disaccharides). Since it acts directly on a food substrate, this option is not the answer.

- **Option B: Lipase**:
- Lipase is an enzyme that acts on fats, converting them into monoglycerides and fatty acids. Since it also acts directly on a food substrate (fats), this option is also not the answer.

- **Option C: Enterokinase**:
- Enterokinase is an enzyme secreted by the intestinal mucosa. It does not act on food substrates directly; instead, it activates another enzyme called trypsinogen, converting it into trypsin. Since enterokinase acts on an enzyme and not directly on food, this option is a strong candidate for the answer.

- **Option D: Trypsin**:
- Trypsin is an enzyme that acts on proteins, breaking them down into smaller peptides. Since it acts directly on a food substrate (proteins), this option is not the answer.

3. **Conclusion**:
- Based on the analysis, the enzyme that does not directly act upon the food substrate in the small intestine of man is **Enterokinase**.

### Final Answer:
**Enterokinase**