Pb-207 NMR spectroscopy reveals that Pb(II) coordinates with glutathione (GSH) and tris cysteine zinc finger proteins in a PbS3 coordination environment.
Pb-207 NMR spectroscopy reveals that Pb(II) coordinates with glutathione (GSH) and tris cysteine zinc finger proteins in a PbS3 coordination environment.
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DOI：
10.1016/j.jinorgbio.2011.04.010
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发表时间：
2011-08
影响因子：
3.9
通讯作者：
Pecoraro, Vincent L.
中科院分区：
文献类型：
--
作者：
Neupane, Kosh P.;Pecoraro, Vincent L.
207 Pb NMR光谱可用于监测Pb（II）与富含巯基的生物小分子（如谷胱甘肽）和锌指蛋白的结合。UV/可见光（UV/维斯）吸收带中心位于334 nM，207 Pb NMR中观察到的207 Pb信号（δ ~ 5750 ppm）表明，在pH 7.5或更高时，谷胱甘肽以三角锥几何构型（PbS 3）结合Pb（II），Pb（II）与GSH的摩尔比为1：3。虽然先前使用UV/维斯和扩展X射线吸收精细结构（EXAFS）光谱的研究被解释为表明来自HIV核衣壳蛋白（HIV-CCHC）的锌结合域在单一PbS 3环境中结合Pb（II），但更灵敏的207 Pb NMR光谱（在pH 7.0，1：1摩尔比下）提供了令人信服的证据，证明存在两种PbS 3结构（δ = 5790和5744 ppm），其中一种在高温下更稳定。先前已经提出HIV-CCHH肽不能正确折叠以提供PbS 2N基序，因为组氨酸不与Pb（II）结合。目前的研究证实了这些预测。这些结果表明，207铅核磁共振的生物分子结构测定的蛋白质半胱氨酸结合位点的第一次的适用性。
207Pb NMR spectroscopy can be used to monitor the binding of Pb(II) to thiol rich biological small molecules such as glutathione and to zinc finger proteins. The UV/visible (UV/Vis) absorption band centered at 334 nM and the observed 207Pb-signal in 207Pb NMR (δ ~ 5750 ppm) indicate that glutathione binds Pb(II) in a trigonal pyramidal geometry (PbS3) at pH 7.5 or higher with a 1:3 molar ratio of Pb(II) to GSH. While previous studies using UV/Vis and extended X-ray absorption fine structure (EXAFS) spectroscopy were interpreted to show that the zinc binding domain from HIV nucleocapsid protein (HIV-CCHC) binds Pb(II) in a single PbS3 environment, the more sensitive 207Pb NMR spectra (at pH 7.0, 1:1 molar ratio) provide compelling evidence for the presence of two PbS3 structures (δ = 5790 and 5744 ppm), one of which is more stable at high temperatures. It has previously been proposed that the HIV-CCHH peptide does not fold properly to afford a PbS2N motif, because histidine does not bind to Pb(II). These predictions are confirmed by the present studies. These results demonstrate the applicability of 207Pb NMR to biomolecular structure determination in proteins with cysteine binding sites for the first time.
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