Which of the following reaction is not catalysed by brush border enzymes ?

Options

A. `"Maltose" overset("Maltase")to"glucose" +"glucose" `
B. `"Lactose" overset("Lactase")to"glucose" +"galactose" `
C. `"Nucleotides" overset("Nucleotidase ")to"Nucleosides" `
D. `"Nucleic acids " overset(" Nucleases ")to"Nucleotides" `

Answer

To determine which reaction is not catalyzed by brush border enzymes, we need to analyze each option provided in the question:

1. **Maltose converted into glucose + glucose by maltase enzyme**:
- This reaction is catalyzed by the brush border enzyme maltase, which is secreted by the epithelial cells of the intestinal villi. Therefore, this option is **not the correct answer**.

2. **Lactose converted into glucose and galactose by lactase enzyme**:
- This reaction is catalyzed by the brush border enzyme lactase, which is also secreted by the brush border cells. Thus, this option is **not the correct answer**.

3. **Nucleotides converted into nucleosides by nucleotidases**:
- This reaction is indeed catalyzed by brush border enzymes, specifically nucleotidases, which are present in the brush border of the intestinal epithelial cells. Hence, this option is **not the correct answer**.

4. **Nucleic acids converted into nucleotides by nucleases**:
- This reaction is **not** catalyzed by brush border enzymes. Instead, it is catalyzed by pancreatic enzymes (nucleases like DNase and RNase) that are secreted by the pancreas into the small intestine. Therefore, this option is the **correct answer**.

### Conclusion:
The reaction that is not catalyzed by brush border enzymes is the conversion of nucleic acids into nucleotides.

### Final Answer:
**Nucleic acids converted into nucleotides by nucleases.**

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