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

通过使用与与 ^<117> ^<117>亚稳态相关的γ射线的时间差异的角相关性，研究了Mavicyanin金属位点（一种具有铜位点的蛋白质分子）周围的结构。它的母核的 ^<117> cd会经历β ^ - 衰减，以填充749 keV激发态 ^<117>的激发状态，半寿命T_ <1/2> = 2.49 h，通过具有旋转I = 3/2，t_ <1/2 up的660 keV InterMediate状态，衰减315 keV激发态Q =（ - ）0.59（1）b。通过在热中性通量为1.93×10^<13> cm^<-2> s^<-2> s^<-1>或2.34×10^<13> cm^<-2> cm^<-2> cm^<-2> s^<-1> kyoto的研究中，通过将富集的^<116> CDO（96.53％）获得约30分钟来获得大约30分钟的父核核^<117> CD。将来自辐照样品溶液的Cd离子在Mavicyanin的金属位点进行，并事先从中提取Cu离子。对样品溶液进行PAC测量。确定野外型Mavicyanin的PAC光谱pH = 6.0、7.5和8.0的PAC光谱为1.48×10^<22>至2.08×10^<22> vm^<-2> 1.49×10^<22> vm^<-2>。与该值相比，在Stellacyanin上报告了1.71×10^<22> VM^<-2>，这项工作中获得的结果似乎是合理的。还发现，对于两种蛋白质，pH值之间的梯度在6.0和7.5之间发生了变化。为了阐明结构中蛋白质的相关变化，对上述几种金属樱桃进行了PAC测量，如上所述进行比较。除此之外，还使用了CD-111M和IN-111衰减PAC问题的其他母体核素进行比较。后来的实验表明，梯度场中蛋白质和金属樱桃之间存在明显的差异，这可能是由于相关配体的协调，并且在测量梯度的测量中存在依赖性。