STRUCTURE-BASED DESIGN, SYNTHESIS, AND BIOLOGICAL EVALUATION OF IRREVERSIBLE HUMAN RHINOVIRUS 3C PROTEASE INHIBITORS - 2 - PEPTIDE STRUCTURE-ACTIVITY STUDIES

The structure-based design, chemical synthesis, and biological evaluat ion of various peptide-derived human rhinovirus (HRV) 3C protease (3CP ) inhibitors are described. These compounds are comprised of an ethyl propenoate Michael acceptor moiety and a tripeptidyl binding determina nt. The systematic modification of each amino acid residue present in the binding determinant as well as the N-terminal functionality is des cribed. Such modifications are shown to provide irreversible HRV-14 3C P inhibitors with anti-3CP activities (k(obs)/[I]) ranging from 60 to 280 000 M-1 s(-1) and antiviral EC50's which approach 0.15 mu M. An op timized inhibitor which incorporates several improvements identified b y the structure-activity studies is also described. This molecule disp lays very rapid irreversible inhibition of HRV-14 3CP (k(obs)/[I] = 80 0 000 M-1 s(-1)) and potent antiviral activity against HRV-14 in cell culture (EC50 = 0.056 mu M). A 1.9 Angstrom crystal structure of an S- alkylthiocarbamate-containing inhibitor complexed with HRV-8 3CP is al so detailed.