通过高分辨率的13C场循环NMR光谱测定囊泡中的脂胆"摇摆"
V N Sivanandam1, Jingfei Cai, Alfred G Redfield
1Department of Chemistry and Biochemistry and the Rosenstiel Basic Medical Sciences Research Institute, Brandeis University, Waltham, Massachusetts 02454, USA.
Journal of the American Chemical Society
|February 27, 2009
概括
高分辨率的碳-13 NMR场循环揭示了囊泡中的脂动态. 胆固醇会影响碳-13和-31的动态,这表明局部运动受到抑制.
科学领域:
- 生物物理学的生物物理.
- 生物化学 生物化学
- 核磁共振 (NMR) 光谱学 核磁共振 (NMR) 光谱学
背景情况:
- 脂是生物膜的关键组成部分,了解它们的动态对于细胞功能至关重要.
- 核磁共振 (NMR) 光谱是一种用于探测分子动态的强大工具.
- 之前的研究已经使用NMR调查了脂动态,但高分辨率 (13) CNMR场循环提供了新的见解.
研究的目的:
- 通过使用高分辨率 (13) C NMR 场循环,研究囊中的酸丁胆的sn-2 碳位的动态.
- 为了比较同一个脂的 (13) C 位点与 (31) P 位点的动态.
- 为了确定胆固醇对脂动态的影响.
主要方法:
- 高分辨率的 (13) C NMR 场循环实验是在广泛的磁场 (11.7 到 0.002 T) 上对酸丁胆囊进行的.
- 测量和分析了自旋格子放松率 (R(1) 以确定相关时间 (tau(c)) 和双极和化学转移异构性 (CSA) 放松的贡献.
- 实验包括和没有胆固醇进行,以评估其对动态的影响.
主要成果:
- 在sn-2碳烯位置的旋晶格放松率 (R(1) 具有二极和CSA放松元件的特征,其中关联时间占主导地位 (tau(c)).
- 还观察到更快的运动成分有助于CSA放松.
- 发现 (13) C 位点的相关性时间 (tau ((c)) 比缺乏胆固醇的 (31) P 位点慢2-3 倍.
- 胆固醇使13C和 (31) P位点的陶增加到大约25 ns,这表明更快的局部运动受到抑制.
结论:
- 在sn-2碳烯位置的动力学由较慢的旋转或摇摆主导,而 (31) P放松受到更快的局部运动的影响.
- 胆固醇通过抑制更快的局部运动,显著影响脂动态.
- 高分辨率的 (13) C 场循环是一种有价值的方法来量化复杂系统中的分子动力学,前提是可以结合合适的 (13) C 标签.
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