Dipyrenylphosphatidylcholines as membrane fluidity probes. Relationship between intramolecular and intermolecular excimer formation rates.
Dipyrenylphosphatidylcholines as membrane fluidity probes. Relationship between intramolecular and intermolecular excimer formation rates.
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二芘基磷脂酰胆碱作为膜流动性探针。
DOI：
10.1016/s0006-3495(90)82531-5
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发表时间：
1990
影响因子：
3.4
通讯作者：
Eisinger,J
中科院分区：
文献类型：
--
作者：
Vauhkonen,M;Sassaroli,M;Somerharju,P;Eisinger,J
在分子内准分子膜探针，二芘磷脂酰胆碱（dipyn PC），芘部分连接到两个酰基链的末端碳，其中每个含有n个碳。我们在这里展示了如何探针分子内激基缔合物的生产率，K，可以确定从激基缔合物/单体的强度比，rl，通过利用相关的monopyrenyl探针，pyn PC，分析根据研磨人群模型的荧光滴定。rl和dipy 10 PC在四个模型膜系统的速率K进行了测量，在一个很宽的温度范围内，这两个参数被证明是主体基质的侧向流动性的敏感功能。提出了一个与分子内和分子间激基缔合物形成速率有关的模型，根据该模型，这两个过程都受到芘部分的再取向速率的限制。在流体-凝胶转变温度Tc以上，单芘基探针（pyn PC）的扩散速率（f）相应地与K相关：pE约为K/（K + 1/2f + tau-1 M），其中pE是最近邻pyn PC探针之间激基缔合物形成的概率，tau M是单体寿命。发现以这种方式导出的pE值与从荧光产率滴定实验的研磨群分析导出的pE值一致。DMPC多层膜中dipy 10 PC的K值在10 ℃凝胶相中为0.21 × 10（7）s-1，在60 ℃流体相中为5.7 × 10（7）s-1，而在相同双层膜中py 10 PC的横向扩散系数D值在8 - 34 μ m2 s-1之间，当用D= fL 2/4计算时，L是宿主膜的平均脂质-脂质间距。高于Tc和在相同的还原温度下，（T-Tc）/Tc，对于py 10 PC，f和对于dipy 10 PC，K的相对大小顺序为：DPPC大于DMPC大于POPC大于DOPC。这和相似的活化能为f和K表明，旋转的芘部分是限速步骤的横向流动性的py 10 PC和分子内激基缔合物形成dipy 10 PC。
In the intramolecular excimeric membrane probe, dipyrenylphosphatidylcholine (dipyn PC), pyrene moieties are linked to the terminal carbons of the two acyl chains, each of which contains n carbons. We show here how the probe intramolecular excimer production rate, K, may be determined from the excimer/monomer intensity ratio, rl, by making use of the fluorescence titrations of the related monopyrenyl probe, pyn PC, analyzed according to the milling crowd model. rl and the rate K of dipy10 PC in four model membrane systems were measured over a wide temperature range and both parameters are shown to be sensitive functions of the lateral fluidity of the host matrix. A model for relating the intramolecular and intermolecular excimer formation rates is proposed according to which both processes are limited by the reorientational rate of the pyrene moiety. Above the fluid-gel transition temperature, Tc, the diffusion rate (f) of the monopyrenyl probe (pyn PC) is accordingly related to K by: pE approximately K/(K + 1/2f + tau -1M), where pE is the probability of excimer formation between nearest neighbor pyn PC probes, and tau M is the monomer lifetime. Values of pE derived in this way are found to be consistent with pE values derived from the milling crowd analysis of fluorescence yield titration experiments. K for dipy10 PC in DMPC multibilayers ranges from 0.21 x 10(7) s-1 at 10 degrees C in the gel phase, to 5.7 x 10(7) s-1 at 60 degrees C in the fluid phase, whereas the lateral diffusion coefficient, D, for py10 PC in the same bilayers ranged from 8 to 34 microns2 s-1, when calculated with D=fL2/4, L being the average lipid-lipid spacing of the host membrane. Above Tc and at the same reduced temperature, (T - Tc)/Tc, both f for py10 PC, and K for dipy10 PC were found to have relative magnitudes in the order: DPPC greater than DMPC greater than POPC greater than DOPC. This and the similarity of the activation energies for f and K suggest that the rotation of the the pyrene moiety is the rate-limiting step for both the lateral mobility of py10 PC and intramolecular excimer formation in dipy10 PC.