Brush border enzymes are enzymes on microvilli; which two examples are correct?

• A. Nuclease and Kinase
• B. Pepsin and Trypsin
• C. Lactase and Maltase
• D. Lipase and Amylase

Answer: (C)

Brush border enzymes sit on the surface of microvilli lining the small intestine, handling the final step of digestion right at the border before absorption. The two enzymes that fit this setting are the disaccharidases that digest sugars into absorbable monosaccharides: lactase splits lactose into glucose and galactose, and maltase splits maltose into two glucose molecules. This localization on microvilli makes the digestion of these disaccharides immediately ready for uptake by the intestinal cells.

The other enzymes listed aren’t typical brush border examples. Nuclease and kinase are not involved in carbohydrate digestion at the microvilli. Pepsin and trypsin are proteases that work in the stomach or in pancreatic secretions, not on the microvilli surface. Lipase and amylase mainly function in the lumen of the gut, not on the brush border membranes.