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稀土离子与乳铁蛋白结合的光谱研究
引用本文:朱兵,杜秀莲,李荣昌,王夔,金坚,王博诚.稀土离子与乳铁蛋白结合的光谱研究[J].高等学校化学学报,2001,22(1):26-30.
作者姓名:朱兵  杜秀莲  李荣昌  王夔  金坚  王博诚
作者单位:1. 北京大学药学院化学生物系,
2. National Key Laboratory of Nuclear Medicine,
基金项目:国家自然科学基金!重大项目 (批准号 :2 9890 2 80 )资助
摘    要:用紫外示差光谱、荧光光谱及圆二色谱等方法研究了 Tb3+ 和 Eu3+ 在 p H 7.4的条件下与乳铁蛋白及脱铁乳铁蛋白的结合作用 .结果表明 ,Tb3+及 Eu3+可特异性地结合在脱铁乳铁蛋白的两个 Fe3+结合部位 ,但不能从已经结合铁的乳铁蛋白中把铁置换出来 .测得 Tb3+与这两个部位结合的条件平衡常数为 lg K1 =8.4 8± 0 .2 4和 lg K2 =6.72± 0 .1 8( 2 5℃ ,0 .1 0 mol/L Na Cl,0 .1 0 mol/L Hepes,p H=7.4 ) . Tb3+ 在这两个位点结合时 ,蛋白质的构象发生变化 .在 Tb3+ 与蛋白质的浓度比低时 ,构象趋于紧缩 ,色氨酸残基进入疏水的环境 ;当 Tb3+ 结合得较多时 ,构象转而开放 ,色氨酸残基转向亲水性环境 .但无论哪种情况 ,Tb3+ 与脱铁乳铁蛋白的结合都不影响蛋白的二级结构 .

关 键 词:乳铁蛋白  脱铁乳铁蛋白  稀土离子  结合作用  生物效应  构象
文章编号:0251-0790(2001)01-0026-05

Spectroscopic Studies on the Binding of Lanthanides to the Apolactoferrin
ZHU Bing,DU Xiu-Lian,LI Rong-chang,WANG Kui,JIN Jian,WANG Bo-cheng.Spectroscopic Studies on the Binding of Lanthanides to the Apolactoferrin[J].Chemical Research In Chinese Universities,2001,22(1):26-30.
Authors:ZHU Bing  DU Xiu-Lian  LI Rong-chang  WANG Kui  JIN Jian  WANG Bo-cheng
Abstract:The binding of Tb3+ and Eu3+ to apolactoferrin has been studied on the basis of the changes in differential UV,fluorescence and CD spectra.It was found that Tb3+ and Eu3+ are able to bind to two ferric-binding sites and the corresponding conditional equilibrium constants for the Tb3+ binding were determined to be lgK1=8.48±0.24,lgK2=6.72±0.18(0.10 mol/L NaCl,0.10 mol/L Hepes,pH 7.4 and 25℃),but Tb3+ can not displace the ferric ions from lactoferrin.By lower Tb3+/Lf ratio,the conformation became more compact with tryptophane residues exposed to more hydrophobic environment.When more Tb3+ bound to Lf ,the conformation changed in other direction.Anyhow,Tb3+ binding did not affect the secondary structure.
Keywords:Lactoferrin  Apolactoferrin  Lanthanide ions
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