金黄色葡萄球菌肠毒素C2中缺口的形成及影响因素的研究

Peptide bond scission of staphylococcal enterotoxin C2 and related factors

目的：探索影响金黄色葡萄球菌肠毒素C2（SEC2）断裂的因素。方法：将纯化的肠毒素在不同条件下处理,观察环境因素对其断裂程度的影响。结果：重组SEC2断裂的位置可能位于其分子93位半胱氨酸与110位半胱氨酸之间。重组SEC2在37℃下、24 h内会完全产生断裂,在碱性条件下则加速其断裂的形成;H2O2会导致重组SEC2产生非特异性降解。当溶液中有β-巯基乙醇（2%）、苯甲基磺酰胺（5-10 mmol/L）、咪唑（1 mol/L）或大肠杆菌粗提物时,重组SEC2的断裂可被有效抑制。结论：肠毒素C2容易在特定位点发生断裂,可能与蛋白质本身结构有关。

Objective： To investigate the limited digestion of recombinant staphylococcal enterotoxin C2 （SEC2 His） in different conditions. Methods： The purified recombinant SEC2 His was treated with different reagents and the cleavage of rSEC2 molecule was observed by SDS- PAGE. Results： The cleavage occurred in positions Cys93-Cys110 of the disulfide loop. Complete auto-cleavage of recombinant SEC2 was observed in solution at 37℃ within 24 hrs,and that was accelerated under alkaline conditions. The auto cleavage of the recombinant protein was inhibited in the presence of β-ME （2%）,PMSF （5-10 mmol/L）,imidazole （1 mol/L） or crude E. coli iysate. Non-specific degradation of recombinant SEC2 was promoted with the increasing of the concentration of H2O2. Conclusion： The recombinant SEC2-His is broken down in special site of protein,which may be associated with the protein structure.