Pepstatin A is a reversible inhibitor of aspartic proteases, Inhibitor for pepsin, renin, cathepsin D, cathepsin G, and other acid proteases. It does not inhibit thiol proteases, neutral proteases or serine proteases. Pepstatin forms a 1:1 complex with acid proteases (carboxyl proteases).
Pepstatin A can be used in conjunction with E64-d and Leupeptin A to inhibit the degradation of autophagic cargo inside autophagosomes.