Characterization of two oxidatively modified phospholipids in mixed monolayers with DPPC
Characterization of two oxidatively modified phospholipids in mixed monolayers with DPPC
复制标题
DOI：
10.1529/biophysj.105.080176
复制
发表时间：
2006-06-01
影响因子：
3.4
通讯作者：
Kinnunen, Paavo K. J.
中科院分区：
文献类型：
--
作者：
Sabatini, Karen;Mattila, Juha-Pekka;Kinnunen, Paavo K. J.
利用Langmuir天平、记录力-面积（pi-A）等温线和表面电位psi研究了两种氧化改性磷脂即1-棕榈酰基-2-（9 '-氧代-壬酰基）-sn-甘油基-3-磷酸胆碱（PoxnoPC）和1-棕榈酰基-2-壬二酰基-sn-甘油基-3-磷酸胆碱（PazePC）的性质。在与1，2-dipalmitoyl-sn-glycero-3-phosphocholine（DPPC）的混合单分子膜中，随着氧化磷脂含量的增加，液体膨胀-液体凝聚转变和膜膨胀逐渐消失。以上与单层的荧光显微镜检查一致，其揭示了DPPC单层的液体膨胀区域的增加。在类似于42 mN/m的临界压力pi（s）下，Poxo-和PazePC均诱导pi-A等温线的偏转，这可以根据氧化改性的酰基链到水相中的重新取向（所谓的延伸构象的适应）来合理化，随后通过将氧化磷脂溶解到水相中来进一步膜压缩。表面电位在相同的面积/分子值下显示出不连续性，对应于氧化磷脂从单层的损失。我们的数据支持这样的观点，即脂质氧化修饰生物膜的小尺度结构动力学以及它们更宏观的横向组织。因此，可以预期氧化修饰的脂质会影响膜相关蛋白的组织和功能。
The properties of two oxidatively modified phospholipids viz. 1-palmitoyl-2-(9'-oxo-nonanoyl)-sn-glycero-3-phosphocholine ( PoxnoPC) and 1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphocholine ( PazePC), were investigated using a Langmuir balance, recording force-area ( pi-A) isotherms and surface potential psi. In mixed monolayers with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine ( DPPC) a progressive disappearance of the liquid expanded-liquid condensed transition and film expansion was observed with increasing content of the oxidized phospholipids. The above is in agreement with fluorescence microscopy of the monolayers, which revealed an increase in the liquid expanded region of DPPC monolayers. At a critical pressure pi(s) similar to 42 mN/m both Poxo- and PazePC induced a deflection in the pi-A isotherms, which could be rationalized in terms of reorientation of the oxidatively modified acyl chains into aqueous phase ( adaptation of the so-called extended conformation), followed upon further film compression by solubilization of the oxidized phospholipids into the aqueous phase. Surface potential displayed a discontinuity at the same value of area/molecule, corresponding to the loss of the oxidized phospholipids from the monolayers. Our data support the view that lipid oxidation modifies both the small-scale structural dynamics of biological membranes as well as their more macroscopic lateral organization. Accordingly, oxidatively modified lipids can be expected to influence the organization and functions of membrane associated proteins.