Question

The lysosomal protease in muscle belonging to family of Aspartic proteases

• A. Cathepsin D
• B. Cathepsin A
• C. Cathepsin B
• D. Trypsin

Hint:

To remember the classification of muscle cathepsins:
- Aspartic Protease: Cathepsin D
- Cysteine Proteases: Cathepsin B, H, L
- Serine Protease: Cathepsin A

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Lysosomal proteases, known as cathepsins, are intracellular enzymes responsible for protein turnover in living cells and the degradation of muscle tissue post-mortem.
These enzymes are classified into different catalytic families based on the chemical nature of the active site.

Step 2: Detailed Explanation:
Cathepsin D is an endopeptidase that belongs to the aspartic protease family, as it utilizes aspartic acid residues for its catalytic activity at acidic pH values.
Cathepsin B is a cysteine protease.
Cathepsin A is a serine protease.
Trypsin is a digestive serine protease found in the pancreatic juices, not in muscle lysosomes.

Step 3: Final Answer:
Thus, Cathepsin D is the lysosomal protease that belongs to the aspartic protease family.