Table 3.

Optimum physical parameters for different enzymes (MEROPS—the protein database, Worthington enzyme manual)

Proteolytic enzyme	Type of enzyme	Active site residues	Optimum temperature	Optimum pH	Enzyme inactivation
Papain	Cysteine endopeptidase	Cysteine, histidine, asparagine	65	6	10 min heating at 90 °C
Pepsin	Aspartic endopeptidase	Aspartic acid	37	2–3	Above pH 7
Trypsin	Serine endopeptidase	Histidine, aspartic acid, serine	37	8	10 min heating at 90 °C
Chymotrypsin	Serine endopeptidase	Histidine, aspartate, serine	37	8	10 min heating at 90 °C
Protease	Serine endopeptidases	Glutamic acid, histidine	37	7	10 min heating at 90 °C