Distinguishing individual lipid headgroup mobility and phase transitions in raft-forming lipid mixtures with 31P MAS NMR
Distinguishing individual lipid headgroup mobility and phase transitions in raft-forming lipid mixtures with 31P MAS NMR
复制标题
DOI：
10.1529/biophysj.105.077289
复制
发表时间：
2006-06-01
影响因子：
3.4
通讯作者：
Alam, Todd M.
中科院分区：
文献类型：
--
作者：
Holland, Gregory P.;McIntyre, Sarah K.;Alam, Todd M.
用静态和魔角旋转P-31核磁共振谱研究了由卵鞘磷脂（SM）、1，2-二油酰-sn-甘油-3-磷酸胆碱（DOPC）和胆固醇组成的模型膜体系。该模型膜系统具有重要的生物相关性，因为已知其形成脂筏。魔角旋转条件下的P-31 NMR解析SM和DOPC头基共振，允许提取各个脂质组分的P-31 NMR参数。各向同性的化学位移，化学位移各向异性，和不对称性参数可以从形成液体有序和液体无序域的各个组件的自旋边带歧管中提取。的P-31化学位移各向异性和线宽的大小被用来确定头基迁移率和监测的凝胶到凝胶和凝胶到液晶相变的SM作为温度的函数，在这些混合物。自旋-自旋弛豫测量与线宽结果一致，反映了迁移率差异和一些异质性。结果表明，在高于和低于液晶相变温度时，DOPC和/或胆固醇的存在极大地影响SM的头基迁移率，而DOPC在这些脂质混合物中仅显示出微小的变化。
A model membrane system composed of egg sphingomyelin (SM), 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), and cholesterol was studied with static and magic angle spinning P-31 NMR spectroscopy. This model membrane system is of significant biological relevance since it is known to form lipid rafts. P-31 NMR under magic angle spinning conditions resolves the SM and DOPC headgroup resonances allowing for extraction of the P-31 NMR parameters for the individual lipid components. The isotropic chemical shift, chemical shift anisotropy, and asymmetry parameter can be extracted from the spinning side band manifold of the individual components that form liquid-ordered and liquid-disordered domains. The magnitude of the P-31 chemical shift anisotropy and the line width is used to determine headgroup mobility and monitor the gel-to-gel and gel-to-liquid crystalline phase transitions of SM as a function of temperature in these mixtures. Spin-spin relaxation measurements are in agreement with the line width results, reflecting mobility differences and some heterogeneities. It will be shown that the presence of DOPC and/or cholesterol greatly impacts the headgroup mobility of SM both above and below the liquid crystalline phase transition temperature, whereas DOPC displays only minor variations in these lipid mixtures.