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MEASUREMENT OF ELECTRIC FIELD GRADIENT AT THE METAL SITES IN PROTEINS

蛋白质金属位点电场梯度的测量

基本信息

批准号：
16550052
负责人：
YOKOYAMA Akihiko
金额：
$ 2.05万
依托单位：
KANAZAWA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16550052/
关键词：
perturbed angular correlation mavicyanin cadmium-117 pH copper protein field gradient metal chelate オキシン後遺効果

项目摘要

The structure around the metal site of mavicyanin, a protein molecule with a copper site, was investigated by using time-differential perturbed angular correlation of γ-rays related to a metastable state of ^<117>In. Its parent nuclei of ^<117>Cd are subjected to β^- decay to populate the 749 keV excited state of ^<117>In with a half-life t_<1/2>=2.49 h, decaying to the 315 keV excited state through the 660 keV intermediate state having a spin I= 3/2, t_<1/2>=53.6 ns, and an electric quadrupole moment Q=(-)0.59(1) b. The parent nuclei ^<117>Cd were obtained by irradiating enriched ^<116>CdO (96.53%) for about 30 min in thermal neutron flux of 1.93×10^<13> cm^<-2>s^<-1> or 2.34×10^<13> cm^<-2>s^<-1> at Kyoto University Research Reactor Institute. The Cd ions from solution of the irradiated sample were substituted in the metal sites of mavicyanin, from which Cu ions were extracted beforehand. The sample solution was subjected to PAC measurements.The field gradient values were determined … More from the PAC spectra of wild-type mavicyanin for pH=6.0, 7.5 and 8.0 to be 1.48×10^<22> to 2.08×10^<22> Vm^<-2>, while those of a mutant-type mavicyanin, Thr15Ala-Mav, were 0.43×10^<22> to 1.49×10^<22> Vm^<-2>. Compared with the value, 1.71×10^<22> Vm^<-2> reported on stellacyanin, the results obtained in this work seem to be reasonable. It was also found that there is a steep change of the gradient between 6.0 and 7.5 in pH for both of the proteins. In order to clarify the relevant change of the proteins in structure, several metal chelates were subjected to the PAC measurement as described above for comparison. In addition to that, additional parent nuclides of Cd-111m and In-111 decaying to PAC probes were used for the experiment for comparison as well. The latter experiment demonstrated that there is clear difference between proteins and metal chelates in gradient fields probably due to coordination of relevant ligands and that there is dependence of the used probes in measurement of the gradients. Less

利用γ射线的时间微分扰动角关联方法研究了具有铜中心的蛋白质分子mavicyanin金属中心周围的结构<117>。它的母核^<117>Cd经过β^-衰变，填充到749 keV的激发态^<117>In，半衰期t1/2>=2.49 h，通过660 keV的中间态衰变到315 keV的激发态，自旋I= 3/2，t1/2>=53.6 ns，电四极矩Q=（-）0.59（1）B.在<117>京都大学研究堆研究所，<116>用1.93×10^<13>cm^<-2>s^<-1>或2.34×10^<13>cm^<-2>s^<-1>的热中子通量辐照富集的^ CdO（96.53%）约30 min，获得了母核^ Cd。从照射样品的溶液中的镉离子取代的金属位点的mavicyanin，从其中铜离子被预先提取。对样品溶液进行PAC测量， ...更多信息野生型mavicyanin在pH=6.0、7.5和8.0时的PAC谱为1.48×10^<22>~ 2.08×10^<22>Vm^<-2>，而突变型mavicyanin Thr 15 Ala-Mav的PAC谱为0.43×10^<22>~ 1.49×10^<22>Vm^<-2>。与星花青苷的1.71×10^<22>Vm^<-2>相比，本工作的结果是合理的。还发现，对于这两种蛋白质，在pH 6.0和7.5之间存在梯度的陡峭变化。为了阐明蛋白质在结构上的相关变化，如上所述对几种金属螯合物进行PAC测量以进行比较。除此之外，还使用了衰变到PAC探针的Cd-111 m和In-111的额外母体核素用于实验以进行比较。后者的实验表明，有明显的差异，蛋白质和金属螯合物在梯度场可能是由于相关配体的配位，并在梯度的测量中使用的探针的依赖性。少