. 2021 Apr 29;11(8):2416–2448. doi: 10.1016/j.apsb.2021.04.001

Table 1.

Main digestive enzymes that degrade PPs along with their sites of action⁴⁴^,⁴⁵.

Secretion site	Enzyme	Specificity
Stomach	Pepsin	Asp, hydrophobic amino acids
Pancreas	Trypsin	Arg, Lys
	Chymotrypsin	Aliphatic amino acids (Phe, Tyr)
	Carboxypeptidase A	Aromatic amino acids in C-terminal (Tyr, Phe, Ile, Thr, Glu, His, Ala)
	Carboxypeptidase B	Arg, Lys in C-terminal
	Elastase	Ala, Gly, Ser
Small intestine	Aminopeptidase A	Asp, Glu in N-terminal
	Aminopeptidase N	Ala, Leu in N-terminal
	Aminopeptidase P	Pro in N-terminal
	Aminopeptidase W	Typ, Tyr, Phe in N-terminal
	γ-Glutamyl transpeptidase	γ-Glutamic acid in N-terminal
	Dipeptidyl peptidase IV	Pro, Ala
	Peptidylpeptidase A	His–Leu
	Carboxypeptidase M	Lys, Arg in C-terminal
	Carboxypeptidase P	Pro, Gly, Ala in C-terminal
	γ-Glutamyl carboxypeptidase	γ-Glutamic acid
	Endopeptidase-24.11	Hydrophobic amino acids
	Endopeptidase-24.18	Aromatic amino acids
	Enteropeptidase	(Asp)₄-Lys