Incorporation of an amino alcohol moiety proved crucial to inhibitory activity for many of these agents. This unit is closely related to the one found in the statine, an unusual amino acid that forms part of the pepstatin, a fermentation product that inhibits protease enzymes.
Adding an amino alcohol group was crucial for the effectiveness of many of these compounds.  This group is similar to one found in statine, a rare amino acid that makes up pepstatin, a substance produced through fermentation that blocks protease enzymes.