RESUMO
It is of popular and scientific knowledge that toxins from snake venom (among them the PLA2 and myotoxins) are neutralized by various compounds, such as antibodies and proteins purified from animal blood. Venomous and nonvenomous snakes have PLA2 inhibitory proteins, called PLIs, in their blood serum. One hypothesis that could explain the presence of these PLIs in the serum of venomous snakes would be self-protection against the enzymes of their own venom, which eventually could reach the circulatory system. However, the presence of PLIs in non-venomous snakes suggests that their physiological role might not be restricted to protection against PLA2 toxins, but could be extended to other functions, as in the innate immune system and local regulation of PLA2s. The present study aimed to review the currently available literature on PLA2 and myotoxin alpha inhibitors present in snake plasma, thus helping to improve the research on these molecules. Furthermore, this review includes current information regarding the mechanism of action of these inhibitors in an attempt to better understand their application, and proposes the use of these molecules as new models in snakebite therapy. These molecules may help in the neutralization of different types of phospholipases A2 and myotoxins, complementing the conventional serum therapy.(AU)
Assuntos
Animais , Elapidae/sangue , Fosfolipases A2 , Trimeresurus/fisiologiaRESUMO
A kininogen-like protein was purified from Bothrops jararaca plasma by DEAE-Sephadex ion-exchange and carboxy-methul-papain-Sepharose affinity chromatography. The molecular weight, estimated by SDS-gel electrophoresis, is about 100,000 and a species of about 75,000 is formed after incubation with hosrse urinary kallikrein. After incubation with rrypsin, only traces of biological activity were detected in tests on guinea pig ileum. The purified protein inhibits papain and bromelain, does not correct the clotting time of a kininogen-depleted human plasma, and does not affect the clotting time ogf plasma from Waglerophis merremii, a nonpoisonous snake; the same type of inhibitor was foind in this nonpoisonous snake. The dissociation cosntant (Ki) for the papain-inhibitor complex is approximately 1.6 nM
Assuntos
Animais , Humanos , Masculino , Feminino , Cininogênios/farmacologia , Cisteína/sangue , Coagulação Sanguínea , Elapidae/sangue , Cromatografia por Troca IônicaRESUMO
Liophis miliaris hemoglobins in the stripped form exhibit a high oxigen affinity, a small alkaline Bohr effect, a pronounce organic polyphosphate effect and a pH-dependent Hill coefficient, close to 2 below pH 7.5 and near 1 at higher pHs. Molecular weight determinations indicate 2 forms, a dimeric form of MW 32000 d. and a tetrameric form of about 64000 d. The deoxyhemoglobin is tetrameric. Ion-exchange chromatography shows two components which may bind to each other being eluted as a single component of MW 32000 d. The osygen alkaline Bohr effect observed for the stripped hemoglobin may be explained by the transition from the tetramer to the dimer during oxygen addition experiments. The phenomenon appears to be unique among animals. ß-Chain sequencing determinations show that abnormal human hemoglobin with similar properties has a glutamic acid residue substituted at the alfa1-ß2 interface by valine in snake hemoglobin