Chemistry and Physics of Lipids ( IF 3.4 ) Pub Date : 2017-12-26 , DOI: 10.1016/j.chemphyslip.2017.12.005 Lina J. Nåbo , Maciej Modzel , Kathiresan Krishnan , Douglas F. Covey , Hideji Fujiwara , Daniel S. Ory , Maria Szomek , Himanshu Khandelia , Daniel Wüstner , Jacob Kongsted
Oxysterols are oxidized derivatives of cholesterol with many important biological functions. Trafficking of oxysterols in and between cells is not well studied, largely due to the lack of appropriate oxysterol analogs. Intrinsically fluorescent oxysterols present a new route towards direct observation of intracellular oxysterol trafficking by fluorescence microscopy. We characterize the fluorescence properties of the existing fluorescent 25-hydroxycholesterol analog 25-hydroxycholestatrienol, and propose a new probe with an extended conjugated system. The location of both probes inside a membrane is analyzed and compared with that of 25-hydroxycholesterol using molecular dynamics simulations. The analogs’ one- and two-photon absorption properties inside the membrane are evaluated using electronic structure calculations with polarizable embedding. Due to predicted keto–enol tautomerisation of the new oxysterol analog, we also evaluate the keto form. Both analogs are found to be good probe candidates for 25-hydroxycholesterol, provided that the new analog remains in the enol-form. Only the new analog with extended conjugated system shows significant two-photon absorption, which is strongly enhanced by the presence of the membrane.
中文翻译:
本征荧光氧固醇的结构设计
氧固醇是胆固醇的氧化衍生物,具有许多重要的生物学功能。氧固醇在细胞内和细胞之间的运输尚未得到很好的研究,这主要是由于缺乏合适的氧固醇类似物。本质上,荧光氧固醇为通过荧光显微镜直接观察细胞内氧固醇的运输提供了一条新途径。我们表征了现有的荧光25-羟基胆固醇类似物25-羟基胆固醇三烯酚的荧光性质,并提出了一种具有扩展共轭体系的新探针。分析两个探针在膜内的位置,并使用分子动力学模拟将其与25-羟基胆固醇的位置进行比较。使用具有可极化嵌入的电子结构计算,评估膜内部类似物的单光子和双光子吸收特性。由于新的氧固醇类似物的酮-烯醇互变异构的预测,我们也评估了酮的形式。如果新的类似物仍以烯醇形式存在,则发现这两种类似物都是25-羟基胆固醇的良好探针候选物。仅具有扩展的共轭体系的新类似物显示出显着的双光子吸收,这通过膜的存在而大大增强。