Purification and biological activity of the thrombin-like substance isolated from Bothrops insularis venom.

The venom of Bothrops insularis snake, known in Brazil as jararaca ilhoa, contains a variety of proteolytic enzymes such as a thrombin-like substance that is responsible for various pharmacological effects. B. insularis venom chromatography profile showed an elution of seven main fractions. The thrombin-like activity was detected in fractions I and III, the latter being subjected to two other chromatographic procedures, so to say DEAE and Hi Trap Benzamidine. The purity degree of this fraction was confirmed by analytical reverse phase HPLC, which displayed only one main fraction confirmed by SDS-PAGE constituting fraction III. About 5 microg of fraction III protein potentiated the secretion of insulin induced by 2.8 mM of glucose in rats isolated pancreatic beta-cells treated; the increase being around 3-fold higher than its respective control. B. insularis lectin (BiLec; 10 microg/mL) was also studied as to its effect on the renal function of isolated perfused rat kidneys with the use of six Wistar rats. BiLec increased perfusion pressure (PP), renal vascular resistance (RVR), urinary flow (UF) and glomerular filtration rate (GFR). Sodium (%TNa+) and chloride tubular reabsorption (%TCl-) decreased at 120 min, without alteration in potassium transport. In conclusion, the thrombin-like substance isolated from B. insularis venom induced an increase in insulin secretion, in vitro, and transiently altered vascular, glomerular and tubular parameters in the isolated rat kidney.