Solution structure calculations through self-orientation in a magnetic field of a cerium(III) substituted calcium-binding protein
Solution structure calculations through self-orientation in a magnetic field of a cerium(III) substituted calcium-binding protein
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DOI：
10.1006/jmre.2000.2218
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发表时间：
2001-01-01
影响因子：
2.2
通讯作者：
Rosato, A
中科院分区：
文献类型：
--
作者：
Bertini, I;Janik, MBL;Rosato, A
在一个研究的框架内，旨在表征顺磁性金属离子能够诱导溶液中的金属蛋白的自取向，我们研究了75个氨基酸的钙结合蛋白D-9 K与一个Ce（III）离子（CaCeCl 2）的复合物。在两种不同的磁场下测定了CaCeCl 3的N-15-H-1（1）J值。上述值显示出对磁场的明显依赖性，这是由溶液中分子的部分取向引起的。在两个磁场下的值的差异提供了结构约束，其已被用于细化CaCeCl 3的结构。精细结构显示出在Ramachandran图的有利区域中的残基数目方面的改进。从N-15-H-1（1）J值获得的分子磁化率张量与从赝接触位移获得的金属磁化率张量的比较表明，溶液中分子的取向主要由Ce（III）离子决定。本文表明，Ce（III），低自旋Fe（III）在血红素蛋白，是足够的磁各向异性诱导自取向的程度，可以利用溶液结构测定。(C)北京：科学出版社.
Within the frame of a research aimed at characterizing paramagnetic metal ions capable of inducing self-orientation of metalloproteins in solution, we have studied the complex of the 75-amino-acid calcium-binding protein calbindin D-9k with one Ce(III) ion (CaCeCb). Backbone N-15-H-1 (1)J values have been determined for CaCeCb at two different magnetic fields. The above values showed a distinct dependence on the magnetic field, which is caused by the partial orientation of the molecule in solution. The difference in the values at the two magnetic fields provides structural constraints, which have been used to refine the structure of CaCeCb. The refined structure showed an improvement in terms of the number of residues falling in favored regions of the Ramachandran plot. The comparison of the molecular magnetic susceptibility tensor, obtained from the N-15-H-1 (1)J values, with the magnetic susceptibility tensor of the metal, obtained from pseudocontact shifts, showed that the orientation of the molecule in solution is mainly determined by the Ce(III) ion. This paper shows that Ce(III), like low-spin Fe(III) in hemoproteins, is sufficiently magnetically anisotropic to induce self-orientation to an extent which can be exploited for solution structure determination. (C) 2001 Academic Press.