高等学校化学学报2009，Vol.30Issue(11)：2154-2158,5.
钙调素与重金属Pb~(2+)结合反应的方波极谱与循环伏安法研究
Direct Binding of Reaction Pb~(2+) to Calmodulin by Square Wave Polarography and Cyclic Voltametry
摘要
Abstract
Calmodulin(CaM) is a highly conserved Ca~(2+) binding protein ubiquitously found in animals and plants, which is involved in a large variety of cellular functions. The presence of many other metal ions in the physiological and nonphysiological environment such as heavy metal ions suggests that CaM might be binding other metal ions than Ca~(2+) , which might influnce CaM's function. It is important to investigate the general metal ion binding properties of CaM. Based on high sensitivity of square wave polarographic signal of Pb~(2+) , the direct binding reaction of Pb~(2+) to CaM was studied by square wave polarography(SWP). The complexing specie, Pb~(2+)-CaM, was detected for the first time by SWP in the Pb~(2+)-CaM system, and electrochemical reaction characterization was done by cyclic voltammetry. Two reduction peaks were detected in SWP polaro-grams obtained at different concentration ratios of Pb~(2+) to CaM at pH = 6.5, indicating that two electroactive species of Pb~(2+) exist, the reduction peak potentials of two species are in the range of - 0.44--0.47 V and - 0.73--0.77 V vs. SCE, respectively. The peak with a maximum at ca. -0.44--0.47 V is corresponding to the reduction of free Pb~(2+) under our experimental conditions and the peak with a maximum at ca.- 0.73--0.77 V, clearly more negative than that for the reduction of free Pb~(2+), allows us to interpret it as due to the reduction of Pb~(2+) complexed by CaM. Moreover, prior to the addition 10 times of Pb~(2+) , two peak currents increase gradually with the increasing of the Pb~(2+) concentration. At higher metal ion concentration (10-16 times), the peak currents of free Pb~(2+) increased linearly with a higher value of the slope, while the peak currents of the complexing specie, Pb~(2+)-CaM, reached maximal and constant. The polarographic titra-tion curves of the two species show that there are ten binding sites in CaM at pH =6.5. Furthermore, the reduction species of Pb~(2+) -CaM system was confirmed by cyclic voltammetry with Controlled Growth Mercury Electrode(CGME).One couple of the free Pb~(2+) redox waves were observed clearly in the cyclic voltammo-gram, and only the reduction peak of the complexing specie of Pb~(2+)-CaM system was detected.The results obtained in the paper show a direct evidence for the mechanism of the toxicity of Pb~(2+) by CaM mediating.关键词
钙调素/重金属离子Pb~(2+)/结合位点/方波极谱法/循环伏安法Key words
Calmodulin/ Heavy metal ion Pb~(2+)/ Binding site/ Square wave polarography/ Cyclic voltammetry分类
化学化工引用本文复制引用
刘德龙,吴彦环,郭慧芳,白娟,孙大业..钙调素与重金属Pb~(2+)结合反应的方波极谱与循环伏安法研究[J].高等学校化学学报,2009,30(11):2154-2158,5.基金项目
国家自然科学基金(批准号: 20475013)资助. （批准号: 20475013）
