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

通过使用与 ^<117>In 其母核 ^<117 的亚稳态相关的 γ 射线的时间微分扰动角相关性，研究了 mavicyanin 的金属位点周围的结构，mavicyanin 是一种具有铜位点的蛋白质分子。 >Cd 发生 β^- 衰变，以半衰期填充 ^<117>In 的 749 keV 激发态t_<1/2>=2.49 h，通过660 keV中间态衰变到315 keV激发态，自旋I= 3/2，t_<1/2>=53.6 ns，电四极矩Q=( -)0.59(1) b.通过照射富集的^ 116 CdO获得母核^ 117 Cd (96.53%) 约 30 分钟，热中子通量为 1.93×10^<13> cm^<-2>s^<-1> 或 2.34×10^<13> cm^<-2>s^<- 1>在京都大学反应堆研究所，将辐照样品溶液中的Cd离子替换到mavicyanin的金属位点上，从中提取出Cu离子。预先对样品溶液进行 PAC 测量。根据野生型 mavicyanin 的 PAC 光谱确定 pH=6.0、7.5 和 8.0 时的场梯度值为 1.48×10^<22> 至 2.08× 10^<22>Vm^<-2>，而突变型mavicyanin的那些，Thr15Ala-Mav，是0.43×10^<22>至1.49×10^<22>Vm^<-2>与星花青素报道的1.71×10^<22>Vm^<-2>值相比，本工作获得的结果似乎是合理的。还发现两种蛋白质的 pH 值在 6.0 和 7.5 之间存在陡峭的变化。为了比较蛋白质的结构，对几种金属螯合物进行了如上所述的 PAC 测量以进行比较。此外，还使用衰变为 PAC 探针的其他母体核素进行比较。后一个实验表明，蛋白质和金属螯合物在梯度场中存在明显差异，可能是由于相关配体的配位，并且在梯度测量中使用的探针存在依赖性。