Received for publication June 14, 2006.
Revised August 28, 2006.
Accepted for publication September 29, 2006.

Short Polybasic Peptide Sequences Are Potent Inhibitors of PC5/6 and PC7: Use of PS-SPCL as a Tool for the Optimization of Inhibitory Sequences

Abstract

Positional Scanning-Synthetic Peptide Combinatorial Libraries (PS-SPCLs) are powerful molecular tools to identify enzyme substrate and potent inhibitory sequences while also providing crucial information about active site determinants. Previously, PS-SPCLs have been surveyed for furin, PC2, PC1/3 and PACE4 and proven efficient to identify potent peptidyl inhibitors in the low nanomolar range for furin and PC1/3. We report herein the screenings of non-amidated and acetylated hexapeptide PS-SPCLs for PC5/6A and PC7. The (L)-library surveys distinctively revealed that (L)-Arg, (L)-Lys and sometimes (L)-His in all six positions would generate the most potent inhibitors for both enzymes. Based on this clear polybasic preference, (L)-polyarginine peptides ranging from 4 to 9 residues were assayed. Inhibitory potency of these polybasic peptides increased with chain length, making nona-(L)-arginine a potent nanomolar inhibitor of PC5/6A and PC7 (K_i of 150 nM and 120 nM). PC5/6 and PC7 inhibition by nona-(L)-arginine was equivalent to that of furin (K_i of 114 nM) (Cameron et al., 2000). Nona-(D)-arginine was a more potent inhibitor of PC5/6 and PC7 than its levorotatory version (K_i of 19 nM and 81 nM), reminiscent of furin (K_i of 1.3 nM) (Kacprzak et al., 2004). Our data indicate that certain poly-arginine peptides represent potent inhibitors targeting PCs of the constitutive secretory pathway (furin, PC5/6 and PC7). We conclude that basic residues within PC peptide inhibitors might be responsible for targeting PCs in general and for inhibitory potency, but that select amino acid changes will be necessary to acquire true specificity toward a single PC.

Key words: Structure-activity relationships and modeling, Combinatorial chemistry, Enzymology, Protein synthesis inhibitors, Neuropeptides, peptidases

This article has been cited by other articles:

				S. A. Shiryaev, A. G. Remacle, B. I. Ratnikov, N. A. Nelson, A. Y. Savinov, G. Wei, M. Bottini, M. F. Rega, A. Parent, R. Desjardins, et al. Targeting Host Cell Furin Proprotein Convertases as a Therapeutic Strategy against Bacterial Toxins and Viral Pathogens J. Biol. Chem., July 20, 2007; 282(29): 20847 - 20853. [Abstract] [Full Text] [PDF]