Faculty of Materials Engineering and Technical Physics, Poznan University of Technology, Piotrowo 3, 61-138 Poznan, Poland.
J Phys Chem B. 2023 Apr 20;127(15):3382-3391. doi: 10.1021/acs.jpcb.3c00654. Epub 2023 Apr 6.
Studies of biological membrane heterogeneity particularly benefit from the use of the environment-sensitive fluorescent probe Laurdan, for which shifts in the emission, produced by any stimulus (e.g., fluidity variations), are ascribed to alterations in hydration near the fluorophore. Ironically, no direct measure of the influence of the membrane hydration level on Laurdan spectra has been available. To address this, we investigated the fluorescence spectrum of Laurdan embedded in solid-supported lipid bilayers as a function of hydration and compared it with the effect of cholesterol─a major membrane fluidity regulator. The effects are illusively similar, and hence the results obtained with this probe should be interpreted with caution. The dominant phenomenon governing the changes in the spectrum is the hindrance of the lipid internal dynamics. Furthermore, we unveiled the intriguing mechanism of dehydration-induced redistribution of cholesterol between domains in the phase-separated membrane, which reflects yet another regulatory function of cholesterol.
研究生物膜异质性特别受益于使用环境敏感荧光探针 Laurdan，因为任何刺激（例如流动性变化）产生的发射位移都归因于荧光团附近水合的变化。具有讽刺意味的是，一直没有直接测量膜水合水平对 Laurdan 光谱影响的方法。为了解决这个问题，我们研究了嵌入固体支撑脂质双层中的 Laurdan 的荧光光谱作为水合作用的函数，并将其与胆固醇的影响进行了比较——胆固醇是一种主要的膜流动性调节剂。这些影响令人费解地相似，因此，应该谨慎解释使用这种探针获得的结果。主导光谱变化的主要现象是脂质内部动力学的阻碍。此外，我们揭示了脱水诱导胆固醇在相分离膜域之间重新分布的有趣机制，这反映了胆固醇的另一种调节功能。
