HIV protease (HIV PR) inhibitor structure-activity-selectivity, and active site molecular modeling of high affinity Leu [CH(OH)CH2]Val modified viral and nonviral substrate analogs

This report details the structure-activity relationships of the HIV gag substrate analog Val-Ser-Gln-Asn-Leu psi[CH(OH)CH2]Val-Ile-Val (U-85548E), an inhibitor exhibiting subnanomolar affinity towards HIV type-1 aspartic proteinase (HIV-1 PR). Our data show that the P1-P2' tripeptidyl sequence provides the minimal chemical determinant for HIV-1 PR binding. We describe the structure-activity properties of Leu psi[CH(OH)CH2]Val substitution in other peptidyl ligands of nonviral substrate origin (e.g., Angiotensinogen, Insulin and pepstatin). Furthermore, the aspartic proteinase selectivities of a few key compounds are summarized relative to evaluation against human Renin, human pepsin, and the Fungal enzyme, rhizopuspepsin. These studies have led to the rational design of nanomolar potent inhibitors of both HIV-1 and HIV-2 PR. Finally, a 2.5 A resolution X-ray crystallographic structure of U-85548E complexed to synthetic HIV-1 PR dimer (Jaskolski et al., Biochemistry 30, 1600 [1991]) provided a 3-D picture of the inhibitor bound to the Enzyme active site, and we performed computer-assisted molecular modeling studies to explore the possible binding modes of the above series of Leu psi[CH(OH)CH2]Val substituted HIV-1 PR inhibitors.