Identification and characterization of a new member of snake venom thrombin inhibitors from Bothrops insularis using a proteomic approach.

Snake venom C-type lectin-like proteins (CLPs) are ubiquitously found in Viperidae snake venoms and differ from the C-type lectins as they display different biological activities but no carbohydrate-binding activity. Previous analysis of the transcriptome obtained from the Bothrops insularis venom gland showed the presence of two clusters homologous to bothrojaracin (BJC) chains alpha and beta. In an effort to identify a new BJC-like molecule, we used an approach associated with proteomic technologies to identify the presence of the expressed protein and then to purify and characterize a new thrombin inhibitor from B. insularis venom. We also constructed homology models of this protein and BJC, which were compared with other C-type lectin-like family members and revealed several conserved features of this intriguing snake venom toxin family.

Proteomic analysis of the ventral disc of Giardia lamblia.

BACKGROUND: Giardia lamblia is a multiflagellated protozoan that inhabits the small intestine of vertebrates, causing giardiasis. To colonize the small intestine, the trophozoites form of the parasite remains attached to intestinal epithelial cells by means of cytoskeletal elements that form a structure known as the ventral disc. Previous studies have shown that the ventral disc is made of tubulin and giardins. RESULTS: To obtain further information on the composition of the ventral disc, we developed a new protocol and evaluated the purity of the isolation by transmission electron microscopy. Using 1D- and 2D-PAGE and mass spectrometry, we identified proteins with functions associated with the disc. In addition to finding tubulin and giardin, proteins known to be associated with the ventral disc, we also identified proteins annotated in the Giardia genome, but whose function was previously unknown. CONCLUSIONS: The isolation of the ventral disc shown in this work, compared to previously published protocols, proved to be more efficient. Proteomic analysis showed the presence of several proteins whose further characterization may help in the elucidation of the mechanisms involved in the attachment of the protozoan to epithelial cells.