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| Author(s): |
Guilherme Henrique Marchi Salvador
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Botucatu. 2016-05-09. |
| Institution: | Universidade Estadual Paulista (Unesp). Instituto de Biociências. Botucatu |
| Defense date: | 2016-02-22 |
| Advisor: | Marcos Roberto de mattos Fontes; Juliana Izabel dos Santos |
| Abstract | |
Bothrops genus represents approximately 90% of the ophidian accidents that occur in Brazil. One of the compounds of the venom is the phospholipases A2 (PLA2s), which are proteins with a wide range of biological activities. Several studies with PLA2s and PLA2-homologues from snake venom were performed to better understanding the myotoxic mechanism, suggesting different activity sites. This work presents studies with PLA2s-homologues isolated from Bothrops moojeni, known in Brazil as caiçaca. The myotoxin II (MjTX-II) was studied in native, complexes to fatty acids, rosmarinic acid and suramin inhibitors. Myotoxin I (MjTX-I) was studied complexed to suramin. X-ray crystallography, dynamic light scattering and isothermal titration calorimetry were used to characterize the protein and complexes. Furthermore, functional studies by myographic techniques and computational studies using molecular dynamics were performed by other members of the Laboratory. Crystallographic structures of MjTX-II in native form and complexes to fatty acids reveals particularities for these toxin, such as the independence of the fatty acids binding for myotoxic residues alignment. The structure of MjTX-II complexed to rosmarinic acid showed that this ligand interact to a of regions related to myotoxic activity of toxin, which probably explaining its inbitory action demonstrated by myographic techniques and is according to previous proposed mechanism. Crystallographic data of the MjTX-II/suramin complex shows two inhibitor molecules interacting to toxin surface, inducing its oligomerization and corroborating with other biophysical experiments. In contrast, MjTX-I/suramin complex crystal structure displayed an oligomeric change from the tetrameric (native) to dimeric structure. (AU) | |
| FAPESP's process: | 12/10830-8 - Structural studies with snake venom phospholipases A2: native, recombinant and complexed with miotoxic activity inhibitors. |
| Grantee: | Guilherme Henrique Marchi Salvador |
| Support Opportunities: | Scholarships in Brazil - Doctorate |