A fraction of cobra （Naja naja atra） venom has been discovered to have protective effect on rat cultural cerebellar granule neurons （CGNs） from apoptosis induced by removing serum and reducing the extracellular po...A fraction of cobra （Naja naja atra） venom has been discovered to have protective effect on rat cultural cerebellar granule neurons （CGNs） from apoptosis induced by removing serum and reducing the extracellular potassium concentration from 25 to 5 mM. This component has been purified and identified as secreted phospholipase A2 （cobra sPLA2）. In order to study the relationship between the protection on CGNs and enzymatic activity of phospholipase A2, CGNs stained by Hoechst 33258 were quantified to determine survival rate under the fluorescence microscopy; the protective potencies on apoptosis of cultural CGNs were compared among cobra sPLA2, the cobra sPLA2 modified in carboxylate groups with water soluble carbodiimide and semicarbazide, and the heated cobra sPLA2 at 80℃ for 30 rain. The results showed that the CGN survival rate was unaffected significantly both in modified cobra sPLAz whose enzymatic activity of PLA2 had decreased by 80%, and in cobra sPLA2 adding 7, 7-Dimethyleicosadienoic acid, an inhibitor of sPLA2 at concentration of 10-fold IC50; contrary, the neuronal survival rate fell about 60% in heated cobra sPLA2, although its PLA2 activity only decreased by 10%. The protection on CGNs were also found in some of sPLA2s derived from venoms of bee, Naja naja mossambica, Crotalus atroxalso and Vipera Ammodytes Ammodytes but could not be found in other sPLA2s from bovine pancreas and Streptomyces violaceoruber. Above results suggest that the protection on CGNs of cobra sPLA2 is independent of its enzymatic activity.展开更多
文摘A fraction of cobra （Naja naja atra） venom has been discovered to have protective effect on rat cultural cerebellar granule neurons （CGNs） from apoptosis induced by removing serum and reducing the extracellular potassium concentration from 25 to 5 mM. This component has been purified and identified as secreted phospholipase A2 （cobra sPLA2）. In order to study the relationship between the protection on CGNs and enzymatic activity of phospholipase A2, CGNs stained by Hoechst 33258 were quantified to determine survival rate under the fluorescence microscopy; the protective potencies on apoptosis of cultural CGNs were compared among cobra sPLA2, the cobra sPLA2 modified in carboxylate groups with water soluble carbodiimide and semicarbazide, and the heated cobra sPLA2 at 80℃ for 30 rain. The results showed that the CGN survival rate was unaffected significantly both in modified cobra sPLAz whose enzymatic activity of PLA2 had decreased by 80%, and in cobra sPLA2 adding 7, 7-Dimethyleicosadienoic acid, an inhibitor of sPLA2 at concentration of 10-fold IC50; contrary, the neuronal survival rate fell about 60% in heated cobra sPLA2, although its PLA2 activity only decreased by 10%. The protection on CGNs were also found in some of sPLA2s derived from venoms of bee, Naja naja mossambica, Crotalus atroxalso and Vipera Ammodytes Ammodytes but could not be found in other sPLA2s from bovine pancreas and Streptomyces violaceoruber. Above results suggest that the protection on CGNs of cobra sPLA2 is independent of its enzymatic activity.
