These results allow us to consider the use of LAAOs as anticancer agents, as tools in biochemical studies to investigate cellular processes, and to obtain a better understanding of the envenomation mechanism.

We report the isolation and structure-function relationship of a 23kDa metalloproteinase named atroxlysin-I from the venom of the Peruvian Bothrops atrox (Jergón). Atroxlysin is a P-I metalloproteinase and contains 204 residues. Its proteolytic activity towards dimethylcasein is enhanced by Ca2+ but inhibited by EDTA, dithiothreitol, excessive Zn2+ and alpha2-macroglobulin. Unlike other structurally homologous P-I metalloproteinases, atroxlysin-I causes hemorrhages. To examine its hemorrhagic activity mechanistically, we studied its function in vitro and in vivo. It cleaved the Ala14-Leu15 and Tyr16-Leu17 bonds in oxidized insulin B-chain and specifically hydrolyzed the alpha-chains of fibrin(ogen) in a dose- and time-dependent manner. Atroxlysin-I cleaved plasma fibronectin and other extracellular matrix proteins (collagens I and IV) and the triple-helical fragment CB3 of collagen IV, but did not degrade laminin-111. Complementarily, the laminin and collagen binding integrins alpha7beta1 and alpha1beta1 were cleaved by atroxlysin. Even without catalytic activity atroxlysin-I inhibited collagen- and ADP-triggered platelet aggregation.

We report the detailed molecular characterization of two PLA2s, Lys49 and Asp49 isolated from Bothrops leucurus venom, and examined their effects against Dengue virus (DENV). The Bl-PLA2s, named BlK-PLA2 and BlD-PLA2, are composed of 121 and 122 amino acids determined by automated sequencing of the native proteins and peptides produced by digestion with trypsin. They contain fourteen cysteines with pIs of 9.05 and 8.18 for BlK- and BlD-PLA2s, and show a high degree of sequence similarity to homologous snake venom PLA2s, but may display different biological effects. Molecular masses of 13,689.220 (Lys49) and 13,978.386 (Asp49) were determined by mass spectrometry. DENV causes a prevalent arboviral disease in humans, and no clinically approved antiviral therapy is currently available to treat DENV infections. The maximum non-toxic concentration of the proteins to LLC-MK2 cells determined by MTT assay was 40 µg/mL for Bl-PLA2s (pool) and 20 µg/mL for each isoform. Antiviral effects of Bl-PLA2s were assessed by quantitative Real-Time PCR. Bl-PLA2s were able to reduce DENV-1, DENV-2, and DENV-3 serotypes in LLC-MK2 cells infection. Our data provide further insight into the structural properties and their antiviral activity against DENV, opening up possibilities for biotechnological applications of these Bl-PLA2s as tools of research.

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