tailieunhanh - Báo cáo khoa học: Kininogen-derived peptides for investigating the putative vasoactive properties of human cathepsins K and L

Macrophages at an inflammatory site release massive amounts of proteolytic enzymes, including lysosomal cys-teine proteases, which colocalizewith their circulating, tight-binding inhibitors (cystatins, kininogens), so modifying the protease/antiprotease equilibrium in favor of enhanced proteolysis. We have explored the ability of human cath-epsins B, KandL to participate in the production of kinins, using kininogens and synthetic peptides that mimic the insertion sites of bradykinin on human kininogens | Eur. J. Biochem. 270 171-178 2003 FEBS 2003 doi Kininogen-derived peptides for investigating the putative vasoactive properties of human cathepsins K and L Claire Desmazes1 Laurent Galineau1 Francis Gauthier1 Dieter Bromme2 and Gilles Lalmanach1 1Laboratoire d Enzymologie et Chimie des Proteines Equipe Proteases et Vectorisation INSERM EMI-U 00 10 Universite Francois Rabelais Faculte de Medecine Tours France -Department of Human Genetics Mount Sinai School of Medicine New York USA Macrophages at an inflammatory site release massive amounts of proteolytic enzymes including lysosomal cysteine proteases which colocalize with their circulating tight-binding inhibitors cystatins kininogens so modifying the protease antiprotease equilibrium in favor of enhanced proteolysis. We have explored the ability of human cathepsins B K and L to participate in the production of kinins using kininogens and synthetic peptides that mimic the insertion sites of bradykinin on human kininogens. Although both cathepsins processed high-molecular weight kininogen under stoichiometric conditions only cathepsin L generated significant amounts of immunoreactive kinins. Cathepsin L exhibited higher specificity constants kcat Km than tissue kallikrein hK1 and similar Michaelis constants towards kininogen-derived synthetic substrates. A 20-mer peptide whose sequence encompassed kininogen residues Ile376 to Ile393 released bradykinin BK 80 and Lys-bradykinin 20 when incubated with cathepsin L. By contrast cathepsin K did not release any kinin but a truncated kinin metabolite BK 5-9 FSPFR 385-389 . Accordingly cathepsin K rapidly produced BK 5-9 from bradykinin and Lys-bradykinin and BK 5-8 from des-Arg9-bradykinin by cleaving the Gly384-Phe385 bond. Data suggest that extracellular cysteine proteases may participate in the regulation of kinin levels at inflammatory sites and clearly support that cathepsin K may act as a potent kininase. Keywords cathepsin cysteine .