Oxidation of unsaturated phospholipids in membrane bilayer mixtures is accompanied by membrane fluidity changes
Oxidation of unsaturated phospholipids in membrane bilayer mixtures is accompanied by membrane fluidity changes
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DOI：
10.1016/s1388-1981(00)00084-6
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发表时间：
2000-08-24
影响因子：
4.8
通讯作者：
Visser, AJWG
中科院分区：
文献类型：
--
作者：
Borst, JW;Visser, NV;Visser, AJWG
稳态和时间分辨荧光光谱已被用来获得信息的氧化过程和相关的动力学和结构变化的模型膜双层由单一单层囊泡（SUV的）的1，2-dioleoyl-sn-甘油-3-磷酸胆碱（DOPC）与增加量的1-硬脂酰-2-花生四烯酸-sn-甘油-3-磷酸胆碱（SAPC）混合。含有四个双键的高度不饱和花生四烯酸链易于氧化，脂质氧化由适当的氧化剂化学引发，并且可以通过掺入的荧光亲脂性脂肪酸4，4-二氟-5-（4-苯基-1，3-丁二烯基）-4-硼-3a，4a-diaza-s-indacene-3-十一烷酸（BP-C11）的荧光变化在线跟踪。氧化速率随着SAPC量的增加而增加。使用荧光相关光谱法对掺入痕量的BP-C11的磷脂酰胆碱类似物的不同SUV的尺寸测量已经证明，脂质不饱和度的增加导致较小尺寸的SUV，并因此导致外双层小叶的较大曲率。这表明脂质-脂质间距增加，并且氧化剂更容易接近不饱和脂肪酰基链。正如使用特异性荧光探针所表明的那样，氧化会导致膜动力学和结构发生一些特征性物理变化。在非氧化和氧化的DOPC-SAPC膜中引入的二芘基和二苯基己三烯标记的PC的荧光测量清楚地表明，当脂质混合物中氧化的SAPC含量增加时，微流动性（在探针的非常位点处的局部流动性）显著降低。从在相同膜系统中使用monopyrenyl PC的侧向扩散实验中观察到类似的效果：在氧化膜中侧向扩散明显较慢。(C)2000 Elsevier Science B. V.保留所有权利。
Steady-state and time-resolved fluorescence spectroscopy has been used to obtain information on oxidation processes and associated dynamical and structural changes in model membrane bilayers made from single unilamellar vesicles (SUV's) of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) mixed with increasing amounts of 1-stearoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (SAPC). The highly unsaturated arachidonoyl chain containing four double bonds is prone to oxidation, Lipid oxidation was initiated chemically by a proper oxidant and could be followed on line via the fluorescence changes of an incorporated fluorescent lipophilic fatty acid: 4,4-difluoro-5-(4-phenyl-1,3-butadienyl)-4-bora-3a,4a-diaza-s-indacene-3-undecanoic acid (BP-C11). The oxidation rate increases with an increasing amount of SAPC. Size measurements of different SUV's incorporated with a trace amount of a phosphatidylcholine analogue of BP-C11 using fluorescence correlation spectroscopy have demonstrated that an increase of lipid unsaturation results in smaller sized SUV's and therefore to a larger curvature of the outer bilayer leaflet. This suggests that the lipid-lipid spacing has increased and that the unsaturated fatty acyl chains are better accessible for the oxidant. Oxidation results in some characteristic physical changes in membrane dynamics and structure, as indicated by the use of specific fluorescence probes. Fluorescence measurements of both dipyrenyl- and diphenylhexatriene-labelled PC introduced in non-oxidised and oxidised DOPC-SAPC membranes clearly show that the microfluidity (local fluidity at the very site of the probes) significantly decreases when the oxidised SAPC content increases in the lipid mixture. A similar effect is observed from the lateral diffusion experiments using monopyrenyl PC in the same membrane systems: the lateral diffusion is distinctly slower in oxidised membranes. (C) 2000 Elsevier Science B.V. All rights reserved.