NON-COVALENT INHIBITORS OF CYSTEINE PROTEASES WITH ATRIPEPTIDE BACKBONE

摘要

The present invention relates to novel noncovalent inhibitors of cysteine proteases that have been designed to mimic the mode of autoinhibition of the propeptides of these enzymes. Just like the propeptide, these peptide-based inhibitors have a reverse binding mode relative to a substrate and span both the S' and S subsites of the enzyme active site. In contrast to previous studies in which even moderate truncation of the full-length propeptide led to rapid reduction in potency, these blocked tripeptide-sized inhibitors maintain nanomolar potency. Moreover, in the case of cathepsin L, these short peptides show higher selectivity (up to 310-fold) for inhibiting cathepsin L over K versus only 2-fold selectivity of the 96-residue propeptide of cathepsin L. A 1.9 Å X-ray crystallographic structure of the complex of cathepsin L with one of the inhibitors confirms the designed reverse-binding mode of the inhibitor as well as its non-covalent nature. Enzymatic analysis also shows the inhibitors to be resistant to hydrolysis at elevated concentrations of the enzyme.