A pentapeptide inhibitor of aspartic proteases; inhibits pepsin, cathepsin D, and HIV protease (IC50s = 50s = 0.32 and 15 µM for the porcine and human enzymes, respectively); inhibits HIV replication in infected H9 cells at 100 µM; decreases gastric acid levels and completely prevents pylorus ulceration in pylorus-ligated rats at 10 and 50 mg/kg