Question

Describe how/where protein digestion occurs in the body and how zymogenic serine proteases contribute to the process.

Answer 1

Digestion of Protein –

1.            From mouth to stomach – When the protein reaches the stomach, it releases gastric juices possessing hydrochloric acid and the pepsin enzyme that breaks down protein. Acidity of stomach unfolds the protein and Pepsin breaks down the protein chains into smaller and smaller fragments.

2.            From stomach to small intestine – Here the pancreas releases digestive juice containing enzyme chymotrypsin and trypsin to digest the protein. Cell lining in intestine releases one more enzyme that break apart the smaller protein fragments into the individual amino acids.

Serine protease enzyme break down peptide bonds in proteins. The serine serves as nucleophilic amino acid at the enzyme site. They are of two major categories - chymotrypsin (released in intestine) and subtilisin