Caracterização estrutural da BpirSP-39 e isolamento e caracterização da primeira serinoprotease do veneno da serpente Bothrops brazili

Abstract

Snake venoms are formed by organic and inorganic compounds and result in a complex product of biological nature which present as main objectives the detention, death and the promotion of initial digestion of its prey. In addition, presents a vast potential for exploration of molecules with pharmaceutical applications. Among organic compounds protease should be highlighted due its ability to cause changes on hemostatic system. Snake venoms serine proteases (SVSPs) are a class of proteases that act on different factors of the coagulation cascade. One SVSPs class is described as thrombin-like (SVTLEs) by mimicking some thrombin activities and displays coagulant ability in vitro through the degradation of fibrinogen chains α and/or β. The objectives were (i) to characterize structurally BpirSP-39 previously isolated from Bothrops pirajai venom and (ii) to isolate and characterize the first serine protease (SP) of B. brazili. Studies of this magnitude are justified because they can provide important information on the involvement of proteins during envenoming, which can contribute to a better understanding of the mechanisms of action of these enzymes. Primary and tertiary structures model of both isolated SPs were elucidated. BpirSP-39 presented 224 amino acids and has high identity when compared to other SVSPs. BbrzSP-32 was obtained from B. brazili venom after two chromatographic steps (affinity and reverse phase) and its primary structure showed 240 amino acid residues. Both SPs characterized are enzymes which may take the SP’s structure of Agkistrodon halys (PDB ID: 4E7N), an enzyme used as a model for molecular modeling. The enzymes are glycoproteins globular and monomeric with two α-helices and two barrels formed by sheet-β. BbrzSP- 32 showed 36 kDa of relative molecular mass and its absolute mass was confirmed by mass spectrometry as 32,520 Da. It present 79.48% identity when compared to other SVSPs and was able to degrade the α-chain of fibrinogen, in vitro models, and is considered a SVTLE-A. It showed a dose-dependent activity in the process of degradation of fibrin networks demonstrating greater specificity for this activity when compared to its thrombolytic action. BbrzSP-32 demonstrated proteolysis activity on gelatin and chromogenic substrates for serine proteases and thrombin-like enzymes (S- 2288 and S-2238 respectively), besides having coagulant activity on human plasma. 13 After pre-incubation with PMSF and benzamidine the coagulants and proteolytic activities on S-2288 and S-2238 substrate were reduced. BbrzSP-32 shows stability against pH and temperature variations, demonstrating optimum activity between 30 and 40 °C and in the pH range 7.5 to 8.5. The enzyme does not induce or interferes with the clotting washed platelets. When incubated with parasites Trypanosoma cruzi or Leishmania infantum, promastigotes and the epimastigote forms, respectively, and S. epidermidis (gram positive-bacteria), the enzyme presented to cytotoxic on microorganisms, furthermore, was able to reduce the biofilm formation by the bacteria species. Both SPs present potential biotechnological.