Four HIV-1 protease (PR) inhibitors, clinical inhibitors lopinavir and tipranavir, and two investigational compounds <b>4 </b> and <b>5 </b>, were studied for their effect on the structure and activity of PR with drug-resistant mutation L76V (PR <s ...
Four HIV-1 protease (PR) inhibitors, clinical inhibitors lopinavir and tipranavir, and two investigational compounds 4 and 5 , were studied for their effect on the structure and activity of PR with drug-resistant mutation L76V (PR L76V ). Compound 5 exhibited the best K i value of 1.9 nM for PR L76V , whereas the other three inhibitors had K i values of 4.5-7.6 nM, 2-3 orders of magnitude worse than for wild-type enzymes. Crystal structures showed only minor differences in interactions of inhibitors with PR L76V compared to wild-type complexes. The shorter side chain of Val76 in the mutant lost hydrophobic interactions with Lys45 and Ile47 in the flap, and with Asp30 and Thr74 in the protein core, consistent with decreased stability. Inhibitors forming additional polar interactions with the flaps or dimer interface of PR L76V were unable to compensate for the decrease in internal hydrophobic contacts. These structures provide insights for inhibitor design.
Organizational Affiliation:
Department of Chemistry and Department of Medicinal Chemistry, Purdue University, West Lafayette, Indiana 47907, United States.,RNA Therapeutics Institute and Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, United States.,Department of Biology, Molecular Basis of Disease Program, Department of Computer Science, and Department of Chemistry, Georgia State University, Atlanta, Georgia 30303, United States.
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