Temperature-induced conformational changes in human tear lipids hydrocarbon chains
Temperature-induced conformational changes in human tear lipids hydrocarbon chains
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DOI：
10.1002/bip.20798
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发表时间：
2007-10-05
期刊：
影响因子：
2.9
通讯作者：
Ho, Donghai V.
中科院分区：
文献类型：
--
作者：
Borchman, Douglas;Foulks, Gary N.;Ho, Donghai V.
作为表征人泪脂的第一步，红外光谱被用于表征碳氢链的分子结构/构象和堆积。温度诱导的相变符合Sigmoid方程，在实验上是可重复性的，对从同一个人采集的多个样本来说也是相似的。没有观察到滞后现象。极性泪脂的水化作用增加了它们的相变协同性、相变焓和相变熵。与泪液脂(TL)相比，MEIBUM脂(ML)中的疏水相互作用更强，这反映在ML的凝胶向液晶的相变中具有更高的熵和热焓。这项研究的结果进一步证明了ML和TL在组成和结构上的差异。观察到的ML碳氢链的构象随温度的变化表明，在眼皮加热下观察到的ML的治疗性增加可能与增加碳氢化合物尾部的堆积无序有关。这项工作还强调了红外光谱在表征人类泪脂的分子结构/构象和堆积方面的能力，并为未来研究泪膜脂质堆积-结构-功能关系和脂-蛋白相互作用与年龄、性别和干眼症状的关系提供了基础。(C)2007年威利期刊公司。
As a first step to characterize human meibum and tear lipids, infrared spectroscopy was applied to characterize the molecular structure/conformation and packing of hydrocarbon chains. Temperature-induced phase transitions were fit to a sigmoid equation and were experimentally reproducible and were similar for multiple samples collected from the same person. No hysteresis was observed. Hydration of polar tear lipids increased their phase transition cooperativity, enthalpy and entropy. Hydrophobic interactions in meibum lipid (ML) were stronger than in tear-fluid lipids (TL), as reflected by the higher entropy and enthalpy of the gel to liquid crystalline phase transition of ML. The results of this study provide further evidence of the differences in the composition and structure of ML and TL. The conformational changes observed in the hydrocarbon chains of ML with temperature suggest that the observed therapeutic increased delivery of ML with eye lid heating could be related to the increased disorder in the packing of the hydrocarbon tails. This work also highlights the power of infrared spectroscopy to characterize molecular structure/conformation, and packing of human tear lipids and provides a basis for future studies of tear film lipid cornposition-structure-function relationships and lipid-protein interactions in relation to age, sex, and dry eye symptoms. (c) 2007 Wiley Periodicals, Inc.