在未溶解中探测螺旋形成
Gary A Breaux1, Martin F Jarrold
1Chemistry Department, Indiana University, 800 East Kirkwood Avenue, Bloomington, IN 47405-7102, USA.
Journal of the American Chemical Society
|August 28, 2003
概括
基于甘氨酸的酸中的相邻的氨酸残留物显著影响螺旋形成. 聚合阿拉宁的酸具有更高的螺旋含量,这表明它们促进螺旋核形成.
科学领域:
- 生物物理化学 生物物理化学
- 类化学 类化学
- 结构生物学 结构生物学
背景情况:
- 了解的二次结构形成,特别是α螺旋,在分子生物学和药物设计中至关重要.
- 未溶解的提供了一个简化的系统来研究内在的折叠倾向,没有溶剂效应.
- 基于甘氨酸的提供了一个独特的结构支架,这是由于甘氨酸的灵活性.
研究的目的:
- 为了研究氨酸残留物定位对未溶解的基于甘氨酸的酸中螺旋体形成的影响.
- 在Ac-[12G3A]K+H+异构体中的氨酸序列的函数中量化螺旋丰度.
- 评估Lifson-Roig理论在预测这些特定的螺旋形成中的适用性.
主要方法:
- 使用离子流动性测量分析了Ac-[12G3A]K+H+的9个序列异构体的气相结构.
- 使用两个不同的指标来量化每个中的螺旋内容.
- 修改后的Lifson-Roig理论被应用到模型中,并与实验性螺旋丰度进行比较.
主要成果:
- 在未溶解中,螺旋的丰富性高度依赖于三种氨酸残留物的接近和位置.
- 具有三个相邻的氨酸的体显示出最高的螺旋丰度.
- 具有良好分离的氨酸的体显示出最低的螺旋丰度,偏离理论预测.
- 修改后的Lifson-Roig理论为大多数提供了合理的适合性,但未能捕捉到关键的实验观测.
结论:
- 邻近的氨酸残留物充当核化部位,显著促进这些的α螺旋形成.
- 观察到的依赖序列的螺旋倾向凸显了折中的局部残留相互作用的重要性.
- 目前的理论模型,如Lifson-Roig理论,可能需要改进,以充分考虑二次结构中特定的残留驱动核化效应.
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