tBid蛋白引发磷脂膜透化过程的研究

Bid蛋白是仅有BH3结构域的Bcl-2家族蛋白,在溶酶体膜透化以及线粒体外膜透化引发的细胞凋亡过程中起着非常重要的调控作用,但是Bid蛋白与生物膜之间的相互作用导致脂膜透化的确切机制尚不十分清楚.本文利用激光扫描共聚焦显微成像技术及基于氧化石墨烯表面诱导荧光衰逝的单分子荧光技术,分别从单囊泡及单分子水平对tBid蛋白与磷脂膜之间的相互作用进行了系统的研究.结果表明,tBid蛋白在膜上聚集后可引起脂膜的透化,且脂膜透化的发生源于聚集体中一些tBid蛋白更深入地插入了脂膜中.     

平板电极间胶体晶体在电场作用下的各向同性压缩

用直径 300 nm的聚苯乙烯微球配制不同浓度的胶体晶体溶液, 将其快速注入内表面镀有导电薄膜的玻璃样品池中, 形成 (111) 晶面平行于玻璃表面的面心立方单晶结构. 通过激光衍射Kossel线方法, 研究了不同体积分数的胶体晶体样品 及它们在均匀电场作用下晶体结构的变化. 实验发现, 随着电场强度的增加, 胶体晶体表现为各向同性的压缩. 胶体晶体在恒定电场下始终保持面心立方结构, 晶格常数随着电场强度的增加逐渐减小. 实验结果可用电场力、电流体力学作用力及颗粒间静电斥力共同解释: 电场力使带电微球克服静电斥力并沿电场反方向运动导致晶体压缩, 而由电场力作用引起的电流体力学液流产生的持续推力使垂直于电场平面上的胶体微球相互靠近. 本实验为天宫一号搭载科学实验的地基实验. 关键词： 胶体晶体 Kossel衍射 结构变化     

固-液界面可聚合脂多层膜的Ｘ射线散射研究

报道在北京同步辐射装置上有关固-液界面的研究结果,在漫散射站成功实现了固-液界面的X射线散射测量.将二乙炔酸的异丙醇溶液滴在硅基底表面,溶剂挥发后形成晶态二乙炔酸多层膜.X射线在位观测实验表明,和水长时间接触后,水分子渗透到多层膜亲水界面,样品呈液晶态.在大尺度上分子膜的热起伏符合液晶的线性弹性理论模型,但小尺度上分子的位移主要由缺陷引起.光照聚全后分子膜的弯曲模量变大,缺陷引发的分子位移范围也增大.     

Two-dimensional polyaniline nanosheets via liquid-phase exfoliation

Two-dimensional(2D) organic nanomaterials are fascinating because of their unique properties and pentential applications in future optoelectronic devices.Polyaniline(PANI) has attracted much attention for its high conductivity,good environmental stability and unusual doping chemistry.We report on liquid-phase exfoliation of layered PANI films grown by electrochemical polymerization.Atomic force microscopy images demonstrate that few-or even mono-layer PANI nanosheets can be fabricated.The PANI nanosheets can be transferred onto a variety of surfaces,providing a promising route to their incorporation into a variety of devices for further studies and various applications.     

丙甲菌素对磷脂膜结构的影响

丙甲菌素是富含α-氨基异丁酸的膜活性肽,能自发插入到脂双层中并相互聚集形成通道结构,对真菌以及革兰氏阳性菌都有抗菌作用.用丙甲菌素与二油酰磷脂酰胆碱的混合溶液在硅片表面制作高度取向的多层膜,并将其浸入水中,用固－液界面X射线散射测量方法,研究了丙甲菌素对磷脂多层膜的结构的影响. 实验结果表明,高浓度条件下,丙甲菌素使脂双层厚度变薄,脂膜的弯曲模量减小.该实验结果有助于理解丙甲菌素与脂双层的相互作用.     

X射线小角散射研究温度对DNA/磷脂复合物结构的影响

报道由短链DNA和磷脂分子在水溶液中形成的复合物的小角散射研究结果. 水溶液中, DNA分子和阳性磷脂分子自发组装成有序的复合多层膜结构: 脂双层相互平行, DNA夹在脂双层之间, 在垂直于DNA方向呈现一维有序结构. 逐渐升高体系的温度, 磷脂双分子膜柔软增加, DNA向双分子层内塌陷, 使多层膜层间距逐渐减小. 而由于DNA分子是一种刚性分子, DNA之间的距离在所测温度 范围内没有变化.     

Growth of Pb S nanoclusters on specific sites of programmed oligodeoxynucleotides

We develope a method to synthesize Pb S nanoclusters(NCs)using guanine-containing oligodeoxynucleotides(ODNs)as templates.The NCs on the ODNs are ultra small(ranging from～0.5 nm to 2.1 nm)and luminescent in the visible region.They are characterized by photoluminescence(PL)spectra,transmission electron microscopy(TEM),and X-ray powder diffraction(XRD).The ODN–NC complexes can be used as customer-designed fluorophores which do not have the problem of multiple conjugations.The same method enables us to fabricate Pb S quantum dot molecules and connect them into nanowires,expanding their potential applications in molecule electronics and quantum computing.     

铜(Ⅱ)与取代酞酰苯胺酸和β-苯丙氨酸混配配合物的研究

酞酰苯胺酸具有突出的生理活性犤１,２犦,其活性随过渡金属配合物生成而增强犤３,４犦,某些氨基酸是人体蛋白质的结构单元,本文报道了铜?与取代酞酰苯胺酸、苯丙氨酸混配配合物的合成、表征及热分解机理。１实验部分１．１配合物的合成酞酰苯胺酸配体的合成按文献犤５犦进行。酞酰苯胺酸与氢氧化钠按１∶１摩尔比溶于热乙醇,苯丙氨酸与氢氧化钠按１∶１摩尔比溶于蒸馏水,分别得到酞酰苯胺酸和苯丙氨酸的钠盐溶液。合并二配体钠盐溶液并置于５０～６０℃水浴中搅拌,按金属盐与每种配体酸１∶１摩尔比缓慢滴入CuAc２水溶液,即有大量…     

Protein–membrane interactions investigated with surface-induced fluorescence attenuation

Research on protein–membrane interactions has been undeveloped due to the lack of proper techniques to detect the position of proteins at membranes because membranes are usually only about 4-nm thick. We have recently developed a new method named surface-induced fluorescence attenuation(SIFA) to track both vertical and lateral kinetics of a single labelling dye in supported lipid bilayers. It takes advantage of strong interaction between a light-emitting dye and a partially reflecting surface. By applying the technique to membrane proteins being fluorescently labelled at different residues, here we show that SIFA can measure not only the insertion depth of a dye inside a lipid bilayer, but also the position of a dye in solution near the surface. SIFA can therefore be used to study membrane proteins of various types.