Abnormal behavior of fluorescence quenching of gramicidin A inphase transition of lipid vesicles by hypocrellin B——Does anelectron transfer inverted region exist?

The fluorescence of gramicidin A(GA) in lipid bilayer may be quenched by Hypocre-Ilin B. When the phospholipids undergo a phase transition from gel to liquid crystalline phase, the reaction rate decreases unusually. This phenomenon has been analyzed by Marcus’ pho-toinduced electron theory, and an electron transfer inverted region hypothesis is proposed,

Quenching of fluorescence in membrane protein by hypocrellin B

The hypocrellin B (HB) was used as a fluorescence quencher to study the basic physical characteris-tics of HB in membrane systems, including the diffusion speed of quencher from aqueous phase into membrane phase, the partition coefficient (P) of quencher between membrane and water, and the fluorescence quenching constant of protein (Ksv; Kq). The experimental results show that the quenching of fluorescence in membrane protein by HB can be determined by the principle of dynamic quenching. The experimental process of fluorescence quenching was ob-served in detail by using the ESR technique. The signal of HB" was found to arise from an electron transfer from ex-cited trytophan to HB.

Raman spectroscopic study of space structure of membrane proteins and membrane lipids in photodamaged human erythrocyte sensitized by hypocrellin B

Laser Raman spectroscopy was used to investigate the photodamage characteristics of human erythrocyte membranes sensitized by hypocrellin B (HB) at the molecular level. It brought to light that the essence of the changes of erythrocyte membranes’ functions caused by membrane protein cross linking and membrane lipid peroxidation, including increase of fluidity and ion permeability of membranes, etc., was that the orderly structure of erythrocyte membranes had been damaged by the active oxygen ( 1O 2, O 2 .- and .OH) generated by HB, including the decrease of α helix, β sheet and the increase of random coil in the main chain of membrane proteins, the decrease of mercapto groups, indole rings, p hydroxy phenyl rings, monosubstituted phenyl rings, etc. in the side chain, and the changes of the conformations of membrane lipids as well. With the increase of the irradiation time, the trans conformation of membrane lipids increased first, then decreased. On the contrary, the gauche conformation decreased first, then increased. In addition, the decrease of the intensities of the lines assigned to bending vibration of the conformation insensitive CH 2 and CH 3 of membrane proteins and lipids suggested that break of their chains had occurred.

竹红菌乙素对人红细胞膜蛋白荧光猝灭机理的研究

本文利用人红细胞膜蛋白内源荧光(主要指色氨酸),经加入不同的竹红菌乙素之后,引起了荧光猝灭现象,根据荧光猝灭原理分别从吸收光谱,荧光光谱,稳态变温实验和瞬态荧光等技术分析了上述的猝灭过程,实验证明:该猝灭是以动态碰撞过程为主要作用机理,据此作者提出了乙素可以用于生物膜体系的蛋白质荧光猝灭剂的理由。

不同状态血红蛋白对红细胞膜功能的影响

用荧光猝灭法测定了不同状态游离血红蛋白和红细胞血影膜间的相互作用,观察到和氧合血红蛋白相比,脱氧血红蛋白和膜上高亲和位点的作用加强,而高铁血红蛋白和低亲和位点的作用加强。本文用低渗溶血速率、阴离子通透性、变形性等三个参量测定了这种相互作用的变化对红细胞膜功能的影响,并讨论了脱氧状态下这种改变的生理意义。

竹红菌乙素作猝灭剂研究F_o构象方法的建立

线粒体Ｆ１Ｆｏ复合体Ｆｏ部分ａ亚基的色氨酸荧光可被竹红菌乙素（ｈｙｐｏｃｒｅｌｉｎＢ，ＨＢ）猝灭．不同温度下测定ＳｔｅｒｎＶｏｌｍｅｒ图的结果显示，猝灭常数（Ｋｓｖ）随温度的增加而加大，时间衰变荧光的结果显示，荧光寿命随ＨＢ浓度的增加而减小，加入不同浓度的ＨＢ，Ｆ１Ｆｏ复合体的吸收峰没有位移．这些实验结果支持动态猝灭机理．ＨＢ还具有有效猝灭浓度低，不影响酶的活力；在脂相和水相的分布比率可高达１６５６０∶１；实验操作简便等优点．因此ＨＢ可作为理想的疏水相荧光猝灭剂，研究与膜结合的Ｆ１Ｆｏ复合体中镶嵌于膜脂内Ｆｏ的构象变化．

竹红菌乙素对菌紫质荧光的影响

用荧光光谱方法研究了竹红菌乙素与菌紫质的相互作用。通过竹红菌乙素对菌紫质吸收光谱，对菌紫质荧光猝死的浓度和温度的依赖性以及竹红菌乙素对明暗适应菌紫质的荧光猝灭等研究表明，竹红菌乙素是一种新型的荧光猝灭剂，它对菌紫质的荧光猝灭属于动态猝死过程。竹红菌乙素对明暗适应菌紫质荧光猝灭的差别，说明这种猝灭剂可用于生物膜体系的蛋白质构象变化的研究。

用荧光探剂比较NO2^—和Cl^—的跨膜通透特性

荧光探剂ＳＰＱ（６－甲氧基－Ｎ－硫代丙基）喹啉－翁）的荧光除了能被Ｃｌ－猝灭外，还能被猝灭，后者的Ｓｔｅｒｎ－Ｖｏｌｍｅｒ猝灭常数Ｋ＝０．２４４（ｍｍｏｌ／Ｌ）－１，约为Ｃｌ－的二倍。据此，用停流技术根据荧光衰减的动力学，给出了重封ＳＰＱ血影膜对阴离子通透的初始速率表达式，比较了及跨膜交换特性。结果表明，二者最大通透速率相近，但对跨膜运输位点的亲和性约为ＣＩ－的５．７倍。

苯肼对红细胞膜结构和功能的影响

通过对低渗溶血过程、荧光淬灭效应及阴离子跨膜通透性的研究,探讨了苯肼对红细胞膜结构和功能的影响。苯肼浓度0.01mM时,低渗溶血的K_1快过程开始变慢,表明膜脂质流动性的降低。苯肼浓度增至0.1mM后,膜和变性血红蛋白的结合大为增强,这种膜结构的变化提高了阴离子的跨膜通透性。