Proteases in Food Digestion: Pepsin, Trypsin, Chymotrypsin, Elastase, Carboxypeptidases, and Microbial Enzymes

Proteases hydrolyze peptide bonds to liberate amino acids. Key dietary proteases:

1. Pepsin – Stomach; active at pH 1‑2; aspartic protease; cleaves aromatic/dicarboxylic bonds.
2. Trypsin & Chymotrypsin – Pancreatic serine proteases; trypsin cuts after Lys/Arg; chymotrypsin after Phe/Trp/Tyr.
3. Elastase – Pancreatic; targets small non‑polar residues (Ala, Gly, Ser, Thr); degrades elastin.
4. Carboxypeptidases A & B – Exopeptidases; release C‑terminal aromatic/hydrophobic (A) or basic (B) amino acids.
5. Microbial proteases – Fungal (Aspergillus, Rhizopus) and bacterial (Bacillus, Lactobacillus) used in fermentation (cheese, soy sauce, meat tenderizing).

Sequential action yields absorbable amino acids and peptides.