Site-specific interactions of copper(II) ions with heparin revealed with complementary (SRCD, NMR, FTIR and EPR) spectroscopic techniques
Site-specific interactions of copper(II) ions with heparin revealed with complementary (SRCD, NMR, FTIR and EPR) spectroscopic techniques
复制标题
DOI：
10.1016/j.carres.2007.12.019
复制
发表时间：
2008-08-11
影响因子：
3.1
通讯作者：
Yates, E. A.
中科院分区：
文献类型：
--
作者：
Rudd, T. R.;Skidmore, M. A.;Yates, E. A.
使用几种互补的光谱技术之间的相互作用Cu（II）离子和肝素进行了研究。NMR表明初始结合相涉及与结构中的四个点的特异性配位，这些点在整个肝素链的略微不同的环境中重复出现;艾杜糖醛酸-2-O-硫酸酯的羧酸基团和环氧，该残基与相邻（朝向还原端）葡糖生丁和6-O-硫酸酯基团之间的糖苷氧。相比之下，后期结合相几乎没有结构特异性。一维和二维相关FTIR显示，复杂的相位（异步）构象变化也发生在滴定过程中的Cu（II）离子肝素，涉及C=O和N-H的伸缩。EPR表明，在最初的结合相的Cu（II）离子的环境是tetraxylate（与略有不同的几何形状），而后来的非特异性相表现出传统的协调。可见光谱法证实了最大吸光度的偏移。将Cu（II）离子滴定到肝素溶液中表明（均通过FTIR和EPR光谱分析）初始结合相由每条链15-20个Cu（II）离子完成;此后离子以非特异性模式结合。异相关光谱法（FTIR-CD）提高了分辨率，并从FTIR光谱中辅助分配了宽CD特征，并表明在Cu（II）离子滴定过程中肝素分子内相互作用的同相和更复杂的异相（分别为同步和异步）变化。(C)2008爱思唯尔有限公司保留所有权利。
The interactions between Cu(II) ions and heparin were investigated using several complementary spectroscopic techniques. NMR indicated an initial binding phase involving specific coordination to four points in the structure that recur in slightly different environments throughout the heparin chain; the carboxylic acid group and the ring oxygen of iduronate-2-O-sulfate, the glycosidic oxygen between this residue and the adjacent (towards the reducing end) glucosantine and the 6-O-sulfate group. In contrast, the later binding phase showed little structural specificity. One- and two-dimensional correlated FTIR revealed that complex out of phase (asynchronous) conformational changes also occurred during the titration of Cu(II) ions into heparin, involving the C=O and N-H stretches. EPR demonstrated that the environments of the Cu(II) ions in the initial binding phase were tetragonal (with slightly varied geometry), while the later non-specific phases exhibited conventional coordination. Visible spectroscopy confirmed a shift of the absorbance maximum. Titration of Cu(II) ions into a solution of heparin indicated (both by analysis of FTIR and EPR spectra) that the initial binding phase was complete by 15-20 Cu(II) ions per chain; thereafter the ions bound in the nonspecific mode. Hetero-correlation spectroscopy (FTIR-CD) improved resolution and assisted assignment of the broad CD features from the FTIR spectra and indicated both in-phase and more complex out of phase (synchronous and asynchronous, respectively) changes in interactions within the heparin molecule during the titration of Cu(II) ions. (C) 2008 Elsevier Ltd. All rights reserved.