Effect of lysophosphatidylcholine on behavior and structure of phosphatidylcholine liposomes

Differential scanning calorimetry (DSC), fluorescence polarization and X-ray diffraction were per-formed to investigate the kinetics of the micellar to the lamellar phase transition of dipalmitoylphosphatidylcholine/1-palmitoylphosphatidylcholine (16:0 LPC/DPPC) liposomes at gel phase. With a 16:0 LPC concentration up to 27 mol% only the sharp main transition with relatively high enthalpy (△H) values of DPPC was observed. Increasing 16 : 0 LPC concentration, the phase transition was broadened and the transition enthalpy was decreased and finally totally disappeared. The fluorescence probes of 3AS, 9AS, 12AS, and 16AP were employed, respectively, to detect the mo-bility of various sites of carbon chains of DPPC or 16:0 LPC/DPPC liposomes. It was shown that DPPC liposomes formed in the absence of 16:0 LPC always had a fluidity gradient in both gel and liquid-crystalline phase, while in the presence of 14.1 mol% and 27.0 mol% 16:0 LPC in the mixtures, the fluidity gradient tended to disappear below 40℃:     

几种超分辨率荧光显微技术的原理和近期进展

在生命科学领域,人们常常需要在细胞内精确定位特定的蛋白质以研究其位置与功能的关系．多年来,宽场/共聚焦荧光显微镜的分辨率受限于光的阿贝/瑞利极限,不能分辨出200 nm以下的结构．近年来,随着新的荧光探针和成像理论的出现,研究者开发了多种实现超出普通共聚焦显微镜分辨率的三维超分辨率成像方法．主要介绍这些方法的原理、近期进展和发展趋势．介绍了光源的点扩散函数(point spread function, PSF)的概念和传统分辨率的定义,阐述了提高xy平面分辨率的方法．通过介绍单分子荧光成像技术,引入了单分子成像定位精度的概念,介绍了基于单分子成像的超分辨率显微成像方法,包括光激活定位显微技术(photoactivated localization microscopy, PALM)和随机光学重构显微技术(stochastic optical reconstruction microscopy, STORM)．介绍了两大类通过改造光源的点扩散函数来提高成像分辨率的方法,分别是受激发射损耗显微技术(stimulated emission depletion, STED)和饱和结构照明显微技术(saturated structure illumination microscopy, SSIM)．比较了不同的z轴提取信息的方法,并阐述了这些方法与xy平面上的超分辨率显微成像技术相结合所得到的各种三维超分辨率显微成像技术的优劣．探讨了目前超分辨率显微成像的发展极限和方向．     

与红细胞带3蛋白55KD片段重组后的DMPC脂质体热相变行为的研究

提纯的红细胞带３蛋白的跨膜阴离子结构域（５５ＫＤ）与ＤＭＰＣ脂质体重组并用ＤＳＣ仪测定了重组体的热相交行为,５５ＫＤ在ＤＭＰＣ重组体上表现的转运ＤＰＡ—Ｃｌ－的速度常数为０．０４２ｍｉｎ－１,ＤＳＣ实验证明,５５ＫＤ的掺入引起脂相变Ｔｍ和ΔＨ的降低,根据５５ＫＤ的浓度和ΔＨ的关系,推算出一个５５ＫＤ分子约能影响４００个ＤＭＰＣ分子不参加相变,脂相变的协同性随５５ＫＤ浓度的增加而线性地降低,也就是说,相变峰形的加宽。本文讨论了５５ＫＤ可影响ＤＭＰＣ脂质体热相变行为的机理。     

溶血磷脂对磷脂脂质体行为和结构的影响

利用差示量热扫描、荧光标记和X-射线衍射法测定了16:0溶血磷脂酰胆碱(LPC)、二棕榈酰磷脂酰胆碱(DPPC)混合脂质体的物化性质:脂双层相变温度、相变热熔、荧光偏振度、双层脂酰链的厚度,证明含有摩尔分数为14.1%和27.0%LPC的DPPC脂质体可以被LPC诱导呈交插脂双层结构,而交插的深度是LPC浓度的函数,当含量超过摩尔分数为30%LPC,混合脂质体趋向于微团化,脂双层膜结构逐渐被破坏,直至最后形成微团结构.