【摘要】 利用Tb3+荧光光谱,通过Tb.CaM系统的特征光谱在加入Ca2+、La3+和Al3+前后荧光强度的改变,研究了pH值对Ca2+、La3+和Al3+与拟南芥钙调素(CaM)竞争结合作用的影响。结果表明,在中性条件下,金属离子与Tb.CaM系统中Tb3+的竞争能力强弱顺序为:La3+>Ca2+>Al3+,与钙调素的结合力为:Tb3+>La3+>Ca2+>Al3+。在pH值等于4.5的酸性条件下,Ca2+、La3+和Al3+与Tb3+的竞争结合能力较中性条件下弱,同时,稀土在酸性条件下的竞争结合力大于Ca2+和Al3+,Al3+与CaM竞争结合能力在酸性条件下大于Ca2+。竞争实验的结果从分子水平上证实了金属离子可取代Ca.CaM中的Ca2+与钙调素产生竞争性结合,模拟Ca2+4.CaM的行为,且pH值对金属离子与钙调素竞争结合力产生一定影响,揭示了胞外钙调素在酸性和金属离子浓度较高的生理条件下生物效应可能的分子机制。更多还原

【Abstract】 The effects of metal ions Tb3+,Ca2+,La3+ and Al3+on the substitute-binding ability of arabidopsis thaliana calmodulin in different pH value have been studied by Tb3+ fluorescence probe.The competition binding abilities of rare earth ions Tb3+ and La3+ to CaM are higher than that of Ca2+ and the affinity of Ca2+ to CaM is higher than that of Al3+ in the condition of pH value equal to 6.5,however,when the pH value reduced to 4.5 the competition binding abilities of La3+,Ca2+,and Al3+ to CaM are lower than that of neutral condition and the binding ability of Al3+is higher than that of Ca2+.The results comfirmed that metal ions can substitute Ca2+ in Ca2+ 4· CaM system and bind to calmodulin competively and the pH value can influence substitute-binding ability of the metal ions.The experiment has disclosed the molecular mechanism of the biological effects of extracelluler CaM in the condition of acid and high metallic concentration.更多还原