<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>A synthetic peptide-based antiviral agent. As a peptidomimetic substrate containing an unnatural amino acid, allophenylnorstatine, KNI-272 selectively binds to and inhibits the human immunodeficiency virus (HIV) 1 and 2 proteases, thereby preventing cleavage of the gag-pol viral polyprotein and resulting in the release of immature, noninfectious virions. (NCI04)</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>