Proteolysis is the directed degradation (digestion) of proteins by cellular enzymes called proteases or by intramolecular digestion.

Proteolysis is used by the cell for several purposes. They include

  • Removal of N-terminal methionine residues after translation.
  • Removal of the signal sequence of peptides after their transport through a membrane
  • Separation of viral proteins that were translated from a monocistronic mRNA
  • Digestion of proteins from foods as a source of amino acids
  • Conversion of predecessor-proteins (proenzymes, zymogenes, prehormones) into their final structures.

Examples of proteases are trypsin and chymotrypsin.