Purification, crystallization and preliminary X-ray diffraction analysis of a class P-III metalloproteinase (BmMP-III) from the venom of Bothrops moojeni

Determining the Structures of the Snake and Spider Toxins by X-Rays

Snake and spider venom is a complex mixture that contains proteins, peptides, and small organic and inorganic compounds. In contrast to spider venom, snake venom proteins are well known both functionally and structurally. This work describes methods for purification and crystallization of snake and spider venom toxins and their three-dimensional structure determination by X-ray crystallography.

The Sequence and a Three-Dimensional Structural Analysis Reveal Substrate Specificity Among Snake Venom Phosphodiesterases

(1) Background. Snake venom phosphodiesterases (SVPDEs) are among the least studied venom enzymes. In envenomation, they display various pathological effects, including induction of hypotension, inhibition of platelet aggregation, edema, and paralysis. Until now, there have been no 3D structural studies of these enzymes, thereby preventing structure-function analysis. To enable such investigations, the present work describes the model-based structural and functional characterization of a phosphodiesterase from Crotalusadamanteus venom, named PDE_Ca. (2) Methods. The PDE_Ca structure model was produced and validated using various software (model building: I-TESSER, MODELLER 9v19, Swiss-Model, and validation tools: PROCHECK, ERRAT, Molecular Dynamic Simulation, and Verif3D). (3) Results. The proposed model of the enzyme indicates that the 3D structure of PDE_Ca comprises four domains, a somatomedin B domain, a somatomedin B-like domain, an ectonucleotide pyrophosphatase domain, and a DNA/RNA non-specific domain. Sequence and structural analyses suggest that differences in length and composition among homologous snake venom sequences may account for their differences in substrate specificity. Other properties that may influence substrate specificity are the average volume and depth of the active site cavity. (4) Conclusion. Sequence comparisons indicate that SVPDEs exhibit high sequence identity but comparatively low identity with mammalian and bacterial PDEs.

Hemorrhagic metalloproteinase, Cc HSM-III, isolated from Cerastes cerastes venom: Purification and biochemical characterization

Snake venom metalloproteinases are the most abundant toxins in Viperidae venoms. In this study, a new hemorrhagin, Cc HSM-III (66 kDa), was purified from Cerastes cerastes venom by gel filtration, ion exchange, and reversed-phase high-performance liquid chromatographies. The analysis of Cc HSM-III by liquid chromatography with a tandem mass spectrometry revealed 32 peptides sharing a homology with P-III metalloproteinases from Echis ocellatus snake venom. Cc HSM-III displays hemorrhagic activity with a minimal hemorrhagic dose of 5 μg, which is abolished by ethylene diamine tetracetic acid but not by phenylmethylsulfonyl fluoride. The mechanism underlying Cc HSM-III hemorrhagic activity is probably due to its extensive proteolytic activity against type IV collagen. Cc HSM-III induces local tissue damage and an inflammatory response by upregulating both matrix metalloproteinase 2 and 9 in skin of mice. Thus, Cc HSM-III may play a key role in the pathogenesis of C. cerastes envenomation.

Involvement of Nitric Oxide on Bothropoides insularis Venom Biological Effects on Murine Macrophages In Vitro

Viperidae venom has several local and systemic effects, such as pain, edema, inflammation, kidney failure and coagulopathy. Additionally, bothropic venom and its isolated components directly interfere on cellular metabolism, causing alterations such as cell death and proliferation. Inflammatory cells are particularly involved in pathological envenomation mechanisms due to their capacity of releasing many mediators, such as nitric oxide (NO). NO has many effects on cell viability and it is associated to the development of inflammation and tissue damage caused by Bothrops and Bothropoides venom. Bothropoides insularis is a snake found only in Queimada Grande Island, which has markedly toxic venom. Thus, the aim of this work was to evaluate the biological effects of Bothropoides insularis venom (BiV) on RAW 264.7 cells and assess NO involvement. The venom was submitted to colorimetric assays to identify the presence of some enzymatic components. We observed that BiV induced H2O2 production and showed proteolytic and phospholipasic activities. RAW 264.7 murine macrophages were incubated with different concentrations of BiV and then cell viability was assessed by MTT reduction assay after 2, 6, 12 and 24 hours of incubation. A time- and concentration-dependent effect was observed, with a tendency to cell proliferation at lower BiV concentrations and cell death at higher concentrations. The cytotoxic effect was confirmed after lactate dehydrogenase (LDH) measurement in the supernatant from the experimental groups. Flow cytometry analyses revealed that necrosis is the main cell death pathway caused by BiV. Also, BiV induced NO release. The inhibition of both proliferative and cytotoxic effects with L-NAME were demonstrated, indicating that NO is important for these effects. Finally, BiV induced an increase in iNOS expression. Altogether, these results demonstrate that B. insularis venom have proliferative and cytotoxic effects on macrophages, with necrosis participation. We also suggest that BiV acts by inducing iNOS expression and causing NO release.

Crystals on the cover 2013

Editorial.