Department of Chemical Science and Engineering, Osaka University, Toyonaka, Japan.
Colloids Surf B Biointerfaces. 2010 May 1;77(1):117-21. doi: 10.1016/j.colsurfb.2010.01.002. Epub 2010 Jan 13.
The transfer of 22-NBD-cholesterol (22-(N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-23,24-bisnor-5-cholen-3-ol) between two liposome membranes was quantitatively analyzed by using the fluorescence resonance energy transfer (FRET) method. Liposomes labeled with both 22-NBD-cholesterol and a rhodamine-labeled phosphatidylethanolamine (Rh-DHPE) were used as donor liposomes, and the 22-NBD-cholesterol transfer from these donor liposomes to acceptor liposomes prepared from same type of phosphatidylcholine was monitored. The transfer kinetics was found to be composed of a fast and a slow phase, and all kinetic measurements could be fitted with a bi-exponential model. The results obtained indicate that the 22-NBD-cholesterol transfer kinetics between liposome membranes depends on the fluidity of the liposome used and that the curvature may affect the kinetics. Furthermore, the behavior of 22-NBD-cholesterol in lipid membrane is similar to that of the oxysterol 25-hydroxycholesterol rather than cholesterol. It is proposed that 22-NBD-cholesterol can be a useful fluorescent probe to mimic the intermembrane transfer of oxidized cholesterols like 25-hydroxycholesterol, rather than that of cholesterol itself.
通过使用荧光共振能量转移（FRET）方法，定量分析了 22-NBD-胆固醇（22-（N-（7-硝基苯并-2-恶唑-1,3-二唑-4-基）氨基）-23,24-双降-5-胆甾-3-醇）在两个脂质体膜之间的转移。用 22-NBD-胆固醇和罗丹明标记的磷脂酰乙醇胺（Rh-DHPE）标记的脂质体用作供体脂质体，并且监测从这些供体脂质体到由相同类型的磷脂酰胆碱制备的受体脂质体的 22-NBD-胆固醇的转移。发现转移动力学由快速和缓慢相组成，并且所有动力学测量都可以用双指数模型拟合。结果表明，脂质体膜之间的 22-NBD-胆固醇转移动力学取决于所用脂质体的流动性，并且曲率可能会影响动力学。此外，22-NBD-胆固醇在脂质膜中的行为类似于氧化固醇 25-羟胆固醇而不是胆固醇。提出 22-NBD-胆固醇可以用作有用的荧光探针来模拟像 25-羟胆固醇这样的氧化胆固醇的跨膜转移，而不是胆固醇本身的跨膜转移。
