阴离子-pi与盐桥相互作用的相对强度:Gtalpha ((340-350) /罗多普辛系统
Matthew A Anderson1, Benhur Ogbay, Rieko Arimoto
1Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Journal of the American Chemical Society
|June 8, 2006
概括
酸与酸的相互作用在几何上存在,但由于竞争的盐桥,在能量上是微不足道的. 修改结构以去除盐桥可以恢复阴离子-pi相互作用的证据.
科学领域:
- 生物化学 生物化学
- 结构生物学 结构生物学
- 化学物理 化学物理
背景情况:
- 理论上,阴离子和芳香侧链之间的阴离子-pi相互作用可以稳定和蛋白质结构.
- 一个特定的,G ((t) alpha ((340-350),与光激活的罗多素 (R*) 结合,在几何上表明Lys341和Phe350.
研究的目的:
- 为了研究在G{t}alpha{340-350) -R*复合体中拟议的-pi相互作用的能量贡献.
- 探索Phe350芳香环上的电子密度的改变如何影响对R*的结合.
- 为了确定竞争盐桥在影响阴离子-π 相互作用中的作用.
主要方法:
- 利用转移NOE (TrNOE) 的NMR来确定与R*结合的的结构.
- 合成并测试了Phe350类似物与改性环替代剂.
- 创建了Phe350的碳胺类似物,以消除竞争中的盐桥.
主要成果:
- 在几何上,-π 相互作用存在,但对-R* 复合体稳定性的能量贡献很小.
- 在Lys341和Phe350的碳酸盐组之间的盐桥屏蔽了电荷,减少了阴离子-pi相互作用.
- 将C端碳酸盐转化为碳酸胺去除了盐桥,允许实验证实了阴离子-pi相互作用.
结论:
- 虽然在几何上存在,但g{t}alpha{340-350) -R*复合体中的-pi相互作用的能量意义受到主导盐桥的限制.
- 该研究强调了在评估生物分子复合体中的非共价力时考虑竞争相互作用的重要性.
- 准确评估阴离子-π相互作用强度需要仔细考虑所有相互作用物种,包括阴离子.
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