Which of the following enzymes is responsible for the breakdown of proteins into amino acids in the liver?

A Aminotransferase
B Proteasome ✓
C Cathepsin
D Carboxypeptidase

Explanation

The proteasome is a large protein complex that degrades damaged or unneeded proteins into amino acids, which can then be reused for protein synthesis or other cellular processes.

Source

Alberts Molecular Biology of the Cell
Protein Metabolism Biochemistry Protein Degradation Medium MEDICAL Confidence: high