Study on the pH Induced Conformational Change of Plant CaM by Using Tb3+ Luminescence Probe
XIAO Feng-juan1,CHANG Hong2,LIU De-long３
1. Material Science and Engineering Department,Shjiazhuang Railway Institute,Shijiazhuang 050043,China 2. College of Physics Science and Information Engineering,Hebei Normal University,Shijiazhuang 050016,China 3. College of Chemistry,Hebei Normal University,Shijiazhuang 050016,China
Abstract：Calmodulin(CaM) is a ubiquitous Ca2+binding protein of eukaryotes,and regulates a broad spectrum of fundamental cellular processes. It has been established that CaM has both intracellular and extracellular signal transduction functions,but the mechanism of the fact that extracellullar CaM can be activated by Ca2+ has been unclear. In order to establish the binding parameters of Ca2+ to extracellular CaM at high Ca2+level and low pH,Tb3+ fluorescence probe and fluorescence spectroscopy were used to investigate the influence of pH values on the conformational change of plant CaM. The fluorescence spectra in apo-CaM had blue shift and were quenched along with the change of pH value from 7.0 to 2.0. The fluorescence intensity of Ca-CaM system was remarkably lower than that of the Tb-CaM system and the Tyr-sensitized Tb3+ fluorescence in Tb3+-CaM was quenched with the addition of H+. On the basis of the results the relation between fluorescence intensity and conformational change of plant CaM and the mechanism of the changes in Tyr microenvironment induced by pH were discussed. It can be assumed that H+ can not only bind to CaM competiting with Ca2+ or Tb3+ but also alter the hydrophobic environment on the surface of CaM molecules,which may affect the activity of CaM. The study supports the extracellular CaM signal transduction mechanism significantly.
Key words：Tb3+ fluorescence probe;Fluorescence spectroscopy;Conformational change;Calmodulin;pH value
肖凤娟1,常虹2,刘德龙3. 铽离子发光探针研究pH诱导的植物钙调素构象变化[J]. 光谱学与光谱分析, 2007, 27(08): 1560-1564.
XIAO Feng-juan1,CHANG Hong2,LIU De-long３ . Study on the pH Induced Conformational Change of Plant CaM by Using Tb3+ Luminescence Probe . SPECTROSCOPY AND SPECTRAL ANALYSIS, 2007, 27(08): 1560-1564.
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