Flach C R, Mendelsohn R
Department of Chemistry, Newark College of Arts and Science, Rutgers University, New Jersey 07102.
Biophys J. 1993 Apr;64(4):1113-21. doi: 10.1016/S0006-3495(93)81477-2.
Fourier transform-infrared (IR) spectroscopic and electron microscopic studies are reported for 1,2-dimyristoylphosphatidylserine (DMPS) and for DMPS/1,2-dimyristoylphosphatidylcholine mixtures in the presence and absence of Ca2+ ion. The frequency of the methyl symmetric deformation mode near 1,378 cm-1, previously assumed insensitive to changes in lipid morphology, has been found to respond to cochleate phase formation by undergoing an approximately 8 cm-1 increase. The new IR spectroscopic marker at 1,386 cm-1 has been used to identify and verify structures suggested from the phase diagram of J. R. Silvius and J. Gagné (1984. Biochemistry. 23:3241-3247) for this system. In addition, the ability of Mg2+ ion to induce cochleate formation has been demonstrated. Higher Mg2+ than Ca2+ levels are required for this process. Finally, IR spectroscopy has been used to monitor dehydration of the lipid surface through changes in the asymmetric PO2- stretching mode. Dehydration precedes cochleate phase formation (i.e., occurs at a lower Ca2+/phosphatidylserine level).
本文报道了傅里叶变换红外（IR）光谱和电子显微镜研究，研究对象为1,2-二肉豆蔻酰磷脂酰丝氨酸（DMPS）以及存在和不存在Ca2+离子时的DMPS/1,2-二肉豆蔻酰磷脂酰胆碱混合物。先前认为对脂质形态变化不敏感的1378 cm-1附近甲基对称变形模式的频率，已被发现会因形成螺旋状相而增加约8 cm-1。1386 cm-1处的新红外光谱标记已用于识别和验证J. R. Silvius和J. Gagné（1984年，《生物化学》，23:3241 - 3247）为此系统绘制的相图所提出的结构。此外，已证明Mg2+离子诱导螺旋状相形成的能力。此过程所需的Mg2+水平高于Ca2+。最后，红外光谱已用于通过不对称PO2-伸缩模式的变化监测脂质表面的脱水情况。脱水先于螺旋状相形成（即，在较低的Ca2+/磷脂酰丝氨酸水平下发生）。
