The proteolytic activity and cleavage specificity of fibronectin-gelatinase and fibronectin-lamininase

摘要: Human plasma fibronectin contains two latent aspartic proteinases, FN-gelatinase and FN-lamininase. Both enzymes can be generated activated in the presence of Ca2+ from purified cathepsin D-produced 190-kDa fragment. We investigated proteolytic activity cleavage specificity both a range pH 3.5 to 9.0 using B chain oxidized bovine insulin chromogenic peptides as substrates. The inhibition by several natural inhibitors human was also tested. specificities FN-lamininase are similar other major acidic including pepsin, renin, D, HIV-proteinases. mainly hydrolyze three peptide bonds chain, namely Glu-Ala (residues 13-14), Tyr-Leu 16-17), Phe-Phe 24-25). For substrates H-Pro-Thr-Glu-Phe-p-nitro-Phe-Arg-Leu-OH H-Phe-Gly-His-p-nitro-Phe-Phe-Val-Leu-OMe that were cleaved respective values k(cat)/K(M) 105.1 11.8 mM(-1) sec(-1) for FN-gelatinase, 123.2 15.5 maximal activities observed between 5.6 6.3 they became inactivated at value above 8.4. efficiently inhibited alpha2-macroglobulin.