Aromatic tetra-amidines: antiproteolytic and antiesterolytic activities towards serine proteinases involved in blood coagulation and clot lysis

Abstract

The inhibitory effect of 1,3-di-(p-amidinophenoxy)-2,2-bis-(p-amidinophenoxymethyl)propane (TAPP-H), TAPP-halo derivatives (with Cl, Br or I) and benzamidine on the Ancrod, bovine Factor Xa, and human plasmin catalyzed hydrolysis of esters and anilides of amino acids was investigated, at pH 8.1 and 37 degrees, and compared with that shown from these compounds on bovine thrombin and porcine pancreatic kallikrein catalysis. The inhibitory effect of TAPP-H and TAPP-halo derivatives on the proteinases considered, involved, to different extents, in blood coagulation and clot lysis, is higher by at least 10-fold, than that of benzamidine, which binds at the primary specificity subsite (S1) of serine endopeptidases and is commonly taken as a molecular inhibitor model. The high inhibitory effect of aromatic tetra-amidines has been interpreted taking into account an additional productive binding for a second benzamidine or halo-benzamidine moiety to the enzyme surface. Moreover, the data reported here allowed us to clarify the inhibition mechanism (in vitro) of TAPP-H on blood coagulation, induced by the "cancer coagulation factor" produced by the Walker carcinoma in Wistar rats and on the fibrinogen-to-fibrin conversion, and to identify some serine proteinases which act as targets for aromatic tetra-amidines.