Pepsin A

Pepsin A (EC 3.4.23.1, pepsin, lactated pepsin, pepsin fortior, fundus-pepsin, elixir lactate of pepsin, P I, lactated pepsin elixir, P II, pepsin R, pepsin D) is an enzyme. This enzyme catalyses the following chemical reaction

Preferential cleavage: hydrophobic, preferably aromatic, residues in P1 and P1' positions. Cleaves Phe¹-Val, Gln⁴-His, Glu¹³-Ala, Ala¹⁴-Leu, Leu¹⁵-Tyr, Tyr¹⁶-Leu, Gly²³-Phe, Phe²⁴-Phe and Phe²⁵-Tyr bonds in the B chain of insulin

The enzyme is a predominant endopeptidase in the gastric juice of vertebrates.