在气相中保存的疏水性蛋白质-连接体相互作用
Lan Liu1, Dhanashri Bagal, Elena N Kitova
1Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2.
Journal of the American Chemical Society
|November 6, 2009
概括
牛β-乳球蛋白和脂肪酸的气态离子存在于两个结构,快速和缓慢,具有明显的解离障碍. 脂肪酸链的长度会影响快速成分.
科学领域:
- 生物物理化学 生物物理化学
- 质谱测量质量谱测量
- 分子动力学分子动力学
背景情况:
- 牛β-乳糖球蛋白 (Lg) 是一种经过充分研究的蛋白质,具有已知的联结能力.
- 脂肪酸 (FA) 是生物相关的分子,其与蛋白质的相互作用具有重要意义.
- 了解蛋白质连接体复合体的气相行为对于解释质谱数据至关重要.
研究的目的:
- 研究牛肉β-乳糖球蛋白和脂肪酸的气态脱复合物的解离机制.
- 通过实验和计算方法来描述这些复合物的结构和能量特性.
- 阐明脂肪酸链长度和蛋白质结构在复杂稳定中的作用.
主要方法:
- 在气态去质子化 (Lg + FA) 离子上进行了时间解析的热解离测量.
- 用分子动力学模拟来建模复合体内的结构和相互作用.
- 用离子移动性测量证实了不同的结构部件的存在.
主要成果:
- 气态 (Lg + FA) 存在两个非相互转换的结构:快 (f) 和慢 (s) 组件.
- 解离仅通过中性脂肪酸的损失而发生.
- 解离的激活能量对脂肪酸链长度敏感,快速成分显示每个甲基的线性增加,表明类似于溶解的相互作用.
- 缓慢的组件表现出更大的激活能量和对链条长度的不太可预测的依赖性,这表明了额外的稳定相互作用.
- 分子动力学模拟显示了不同的"开放"和"闭合"结构,闭合结构涉及键和非极性相互作用,稳定脂肪酸连接体.
结论:
- 脂肪酸的酸链在气相中的β-乳糖球蛋白的疏水腔内保留.
- 快速成分的分裂屏障主要反映了非极性分子间相互作用的裂变.
- 缓慢元件的解离障碍涉及非极相互作用和键的破坏,与封闭结构模型相一致.
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