Pohle W, Selle C, Fritzsche H, Binder H
Friedrich-Schiller University Jena, Department of Biophysical Chemistry, Germany.
Biospectroscopy. 1998;4(4):267-80. doi: 10.1002/(sici)1520-6343(1998)4:4<267::aid-bspy5>3.0.co;2-#.
An algorithm for the study of the gradual hydration of phospholipid assemblies by means of Fourier transform infrared (FTIR) spectroscopy is presented. A complete series of diacyl phosphatidylcholines (PCs) including all possible analogues with palmitoyl and oleoyl residues, namely DPPC, DOPC, POPC, and OPPC, was investigated at room temperature. The lipid samples were prepared as cast films probably consisting of aligned multilamellar bilayers. The range of water activities studied in these films was regulated by adsorption via the gas phase corresponding to relative humidities of between 0 and 100%. Analyses of the IR-spectroscopic data have concentrated mainly on determining the amounts of water incorporated by each lipid as well as the hydration-induced response observed for some absorption bands of the different lipids. The water uptake at high relative humidity (RH) increases with the portion of unsaturated acyl chains in the molecular structure of the PCs. Isothermal phase transitions triggered lyotropically have been detected in demonstrating the occurrence of the main transition in POPC and OPPC films at room temperature. Moreover, it appears that both lamellar phases, the gel as well as the liquid-crystalline phase, are not uniform. They seem to comprise an amazingly large span of order/disorder states of the lipid chains generally depending on the degree of hydration. As exemplified by the significant variation in the onset of wavenumber shifts for the PO2- and C=O stretching-vibration modes, obtained as a function of hydration, a sequence of attachment to polar lipid binding sites by water molecules was established for DPPC.
本文提出了一种通过傅里叶变换红外（FTIR）光谱研究磷脂组装体逐步水合作用的算法。在室温下研究了一系列完整的二酰基磷脂酰胆碱（PCs），包括所有含有棕榈酰和油酰残基的可能类似物，即二棕榈酰磷脂酰胆碱（DPPC）、二油酰磷脂酰胆碱（DOPC）、1-棕榈酰-2-油酰-sn-甘油-3-磷酸胆碱（POPC）和1-油酰-2-棕榈酰-sn-甘油-3-磷酸胆碱（OPPC）。脂质样品制备成可能由排列的多片层双层组成的铸膜。这些膜中研究的水活度范围通过气相吸附来调节，对应于0%至100%的相对湿度。红外光谱数据分析主要集中在确定每种脂质结合的水量以及不同脂质某些吸收带观察到的水合诱导响应。在高相对湿度（RH）下的吸水量随着PCs分子结构中不饱和酰基链的比例增加而增加。在证明室温下POPC和OPPC膜中主要转变的发生时，检测到了溶致触发的等温相变。此外，似乎层状相，即凝胶相和液晶相，都不均匀。它们似乎包含了脂质链的一个惊人的大的有序/无序状态范围，这通常取决于水合程度。以水合作用函数获得的PO2-和C=O伸缩振动模式波数偏移起始点的显著变化为例，为DPPC建立了水分子与极性脂质结合位点的附着序列。
