title: Barley serine proteinase inhibitor 2-derived cyclic peptides as potent and selective inhibitors of convertases PC1/3 and furin.
abstract: Proprotein convertases (PCs) are serine proteases containing a subtilisin-like catalytic domain that are involved in the conversion of hormone precursors into their active form. This study aims at designing small cyclic peptides that would specifically inhibit two members of this family of enzymes, namely, the neuroendocrine PC1/3 and the ubiquitously expressed furin. We studied peptide sequences related to the 18-residue loop identified as the active site of the 83 amino acid barley serine protease inhibitor 2 (BSPI-2). Peptides incorporating mutations at various positions in the sequence were synthesized on solid phase and purified by HPLC. Cyclization was achieved by the introduction of a disulfide bridge between the two Cys residues located at both the N- and C-terminal extremities. Peptides VIIA and VIIB incorporating P4Arg, P2Lys, P1Arg, and P2'Lys were the most potent inhibitors with K(i) around 4 microM for furin and around 0.5 microM for PC1/3. Whereas peptide VIIB behaved as a competitive inhibitor of furin, peptide VIIA acted as a noncompetitive one. However, all peptides were eventually cleaved after variable incubation times by PC1/3 or furin. To avoid this problem, we incorporated at the identified cleavage site a nonscissile aminomethylene bond (psi[CH(2)-NH]). Those pseudopeptides, in particular peptide VIID, were shown not to be cleaved and to inhibit potently furin. Conversely, they were not able to inhibit PC1/3 at all. Those results show the validity of this approach in designing new effective PC inhibitors showing a certain level of discrimination between PC1/3 and furin.
authors.affiliation: Neuropeptides Structure and Metabolism Unit, Institut de Recherches Cliniques de Montréal, 110 Pine Avenue West, Montréal, Québec, Canada H2W 1R7.
authors.forename: Michèle
authors.initials: M
authors.lastname: Villemure
authors.forename: Alain
authors.initials: A
authors.lastname: Fournier
authors.forename: Dany
authors.initials: D
authors.lastname: Gauthier
authors.forename: Nadia
authors.initials: N
authors.lastname: Rabah
authors.forename: Brian C
authors.initials: BC
authors.lastname: Wilkes
authors.forename: Claude
authors.initials: C
authors.lastname: Lazure
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001120:Arginine / Q000031:analogs & derivatives / Q000378:metabolism; D016282:Aspartic Acid Endopeptidases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D001665:Binding Sites; D001667:Binding, Competitive; D020134:Catalytic Domain / Q000235:genetics; D045683:Furin; D001467:Hordeum / Q000201:enzymology*; D020128:Inhibitory Concentration 50; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000138:chemical synthesis / Q000235:genetics* / Q000494:pharmacology*; D043484:Proprotein Convertases; D015842:Serine Proteinase Inhibitors / Q000138:chemical synthesis / Q000235:genetics* / Q000494:pharmacology*; D013379:Substrate Specificity; D013381:Subtilisins / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D010456:Peptides, Cyclic; D015842:Serine Proteinase Inhibitors; D001120:Arginine; D043484:Proprotein Convertases; D013381:Subtilisins; D045683:Furin; D016282:Aspartic Acid Endopeptidases