leucurus venom ( Sanchez et al., 2007). This result shows that the venom of B. leucurus, and probably also from other species, contains more than one type of dis-cys conjugate. Leucurogin used in the biological assays in this study was purified by a very simple procedure involving one chromatographic step after clarification in a hollow-fiber system. As observed for most recombinant proteins, leucurogin has a strong tendency to Z VAD FMK aggregate in low ionic strength (data not shown). Purified leucurogin was firstly assayed for inhibition of platelet aggregation and the results showed that the recombinant protein is as active as the other natural disintegrins or dis-cys conjugates like that from B. jararaca

( Usami et al., 1994) and KU-60019 mouse Bothrops atrox ( Jia et al., 1997). At micromolar levels leucurogin is able to inhibit 100% of platelet aggregation induced by collagen. No effects were observed upon platelet aggregation induced by ADP or AA. The capacity of leucurogin to inhibit the growth of Ehrlich tumor implanted in mice was also similar to that observed for the 27 kDa protein partially purified from B. leucurus snake venom. By the vascularization levels of a sponge subcutaneously implanted in mice we can conclude that at least partially the effect of leucurogin upon the tumor growth may be due to a

potent inhibition of angiogenesis process. Previous studies have shown that hemoglobin detection correlated well with other methods for the detection and quantification of angiogenesis in tissues ( Hu et al., 1995). In conclusion, this work describes, for the first time, the production of one recombinant disintegrin-like cloned from B. leucurus and shows that this disintegrin, independently of the cysteine rich domain, is able, probably through interaction with integrins α1β1 or α2β1, to inhibit effects many elicited by type I collagen like platelet

aggregation and tumor growth. Leucurogin represents a new tool to understand the biological process where disintegrins-like are involved and may help to characterize integrins that can be involved in development and progression of malignant cells. None. The authors would like to thank to FAEP, Fapemig, Fapesp, CAPES and CNPq for financial support. The authors also thank Dr. Ana M Moura da Silva and Dr. Maisa S Della-Casa from Intituto Butantan, SP, to provide us with the anti-jararhagin antibody. “
“Various studies in recent years have shown that Bothrops venoms ( Zamunér et al., 2004 and Abreu et al., 2007) and their phospholipases ( Gallacci and Cavalcante, 2010) can produce neuromuscular blockade in vitro. Although the principal sites of action for this blockade appear to be postsynaptic, there is evidence for a presynaptic component in this response ( Cogo et al., 1998, Borja-Oliveira et al., 2003 and Rodrigues-Simioni et al., 2004).