ABSTRACT
Objetivo Determinar estrutural básica e modelagem molecular por via comparativa da giroxina, uma serinoprotease trombina símile isolada do veneno da Crotalus durissus terrificus. Métodos As análises de similaridade de estrutura primária e secundária foram geradas através de sistemas logarítmicos e probabilísticos de modo a encontrar um molde proteico da mesma família da giroxina com capacidade de servir de molde para gerar estruturas tridimensionais comparativas da proteína selecionada. Resultados A giroxina é uma proteína com 241 aminoácidos, de caráter ácido, instável e de melhor ação em meio aquoso. Possui um peso molecular de 26.1kDa e 6 prováveis pontes de dissulfeto. Conclusões A giroxina é uma proteína trombina símile com ação na dissolução de coágulos e seu estudo estrutura-atividade pode trazer novos fármacos para embolias pulmonares, infartos cardíacos e trombose de membros baixos. Novos estudos observam a interação da giroxina com receptores PAR-1 de astrócitos o que pode indicar uma nova classe de medicamentos para tratamento de síndromes neurodegenerativas, tais como a síndrome de Parkinson.
Objective To determination basic structure and molecular modeling by comparative means of gyroxin, a serinoproteases trombinelike isolated from the Crotalus durissus terrifius venom. Methods Analysis of similarity of primary and secondary structures generated through logaritmic and probabilistic systems to find a protein model of the same family with capacity to be used as template to create tridimensional comparative structures of the selected protein. Results The gyroxin is a 241 aminoacids protein, of acid qualities, instable and have better activity in water solutions. It has 26.1kDa of molecular weight and 6 probable dissulfide bonds. Conclusions Gyroxin is a trombine-like protein acting to dissolve blood clots and her structure-activity study may bring new drugs to treat pulmonary embolism, cardiac arrest and lower members tromboses. New studies appoint the interaction between gyroxin and PAR-1 astrocytes receptors who may indicate a new class of neurodegeneratives syndromes drugs, such as Parkinson's syndrome.
ABSTRACT
Gyroxin, a thrombin-like enzyme isolated from Crotalus durissus terrificus venom and capable of converting fibrinogen into fibrin, presents coagulant and neurotoxic activities. The aim of the present study was to evaluate such coagulant and toxic properties. Gyroxin was isolated using only two chromatographic steps - namely gel filtration (Sephadex G-75) and affinity (Benzamidine Sepharose 6B) - resulting in a sample of high purity, as evaluated by RP-HPLC C2/C18 and electrophoretic analysis that showed a molecular mass of 30 kDa. Gyroxin hydrolyzed specific chromogenic substrates, which caused it to be classified as a serine proteinase and thrombin-like enzyme. It was stable from pH 5.5 to 8.5 and inhibited by Mn²+, Cu²+, PMSF and benzamidine. Human plasma coagulation was more efficient at pH 6.0. An in vivo toxicity test showed that only behavioral alterations occurred, with no barrel rotation. Gyroxin was not able to block neuromuscular contraction in vitro, which suggests that its action, at the studied concentrations, has no effect on the peripheral nervous system.