Pepstatin A (PepA)

Pepstatin A is a naturally occurring pentapeptide produced by various species of Actinomyces, most notably Streptomyces (Umezawa et al., 1970). It is a potent and specific inhibitor of aspartic proteases, including pepsin, renin, cathepsin D, and HIV protease (Marciniszyn et al., 1976). The molecule functions by mimicking the tetrahedral transition state of peptide bond hydrolysis, specifically through the presence of the unusual amino acid statine, which allows it to bind tightly to the enzyme's active site (Wikipedia). While Pepstatin A is not a therapeutic target itself, it is a critical biochemical tool used to characterize protease function and has served as a structural template for the development of clinically relevant drugs, such as HIV protease inhibitors and antihypertensive agents (NIH). Its research applications span oncology, virology, and cardiovascular science, where it is used to study lysosomal function, viral processing, and bone remodeling (Cell Signaling Technology). Due to its broad-spectrum inhibition of aspartic proteases, it is frequently included in protease inhibitor cocktails for laboratory use (Tocris Bioscience).

Other names

PepstatinIsovaleryl-L-valyl-L-valyl-statyl-L-alanyl-statinePepsin Inhibitor S 735AAhpatinin C

Competitive, reversible inhibition of aspartic proteases by mimicking the tetrahedral transition state of peptide bond hydrolysis.