温度及膜中蛋白质含量与膜粘度和膜中分子排列方向的关系

本实验用闪光诱导的瞬间二向色性方法测量了不同温度以及不同蛋白质含量下菌紫质分子在脂质囊泡膜中的旋转扩散运动.根据旋转扩散运动得到了温度和蛋白质含量与膜粘度以及分子在膜中排列方向的关系.温度和蛋白质的含量都影响膜的粘度,但并不影响蛋白质分子在膜中的排列方向.     

PROTONATION AND CHLOROPLAST MEMBRANE STRUCTURE

Light changes the structure of chloroplasts. This effect was investigated by high resolution electron microscopy, photometric methods, and chemical modification. (a) A reversible contraction of chloroplast membrane occurs upon illumination, dark titration with H⁺, or increasing osmolarity. These gross structural changes arise from a flattening of the thylakoids, with a corresponding decrease in the spacing between membranes. Microdensitometry showed that illumination or dark addition of H⁺ resulted in a 13–23% decrease in membrane thickness. Osmotically contracted chloroplasts do not show this effect. (b) Rapid glutaraldehyde fixation during actual experiments revealed that transmission changes are closely correlated with the spacing changes and therefore reflect an osmotic mechanism, whereas the light scattering changes have kinetics most similar to changes in membrane thickness or conformation. (c) Kinetic analysis of light scattering and transmission changes with the changes in fluorescence of anilinonaphthalene sulfonic acid bound to membranes revealed that fluorescence preceded light scattering or transmission changes. (d) It is concluded that the temporal sequence of events following illumination probably are protonation, changes in the environment within the membrane, change in membrane thickness, change in internal osmolarity accompanying ion movements with consequent collapse and flattening of thylakoid, change in the gross morphology of the inner chloroplast membrane system, and change in the gross morphology of whole chloroplasts.     

金鱼精子质膜和核膜的区域特异性

本文结合采用扫描和透射电子显微镜(包括冷冻断裂-蚀刻、超薄切片以及细胞化学染色法),研究了金鱼精子的超微结构特征,结果表明金鱼精子的质膜和核膜都具有区域特异性:1)精子质膜内大部分区域含有许多蛋白颗粒,但在特定区域内,蛋白颗粒呈有序排列,构成晶格状结构。2)精子头颈部和尾部均有液泡密集之处,凡是覆盖着液泡区的质膜内,几乎都不含有蛋白颗粒。3)液泡区能被细胞化学方法染成致密色,表明内含糖蛋白。4)核膜孔只集中存在于靠近颈部的核膜上,而其他部分则没有。本文对上述诸点进行了讨论。     

三氯乙烯对脂质体膜通透性的影响及其破膜效应

本文通过测定脂质体膜对水的通透性及脂质体对被包裹血红蛋白的释放率,研究了三氯乙烯对脂质体的作用.观察到在低浓度时,三氯乙烯能增加蛋卵磷脂脂质体的通透性,随着浓度的增加有破膜释放的效应.     

BIOCHEMICAL AND MORPHOLOGICAL COMPARISON OF PLASMA MEMBRANE AND MILK FAT GLOBULE MEMBRANE FROM BOVINE MAMMARY GLAND

Purified plasma membrane fractions from lactating bovine mammary glands and membranes of milk fat globules from the same source were similar in distribution and fatty acid composition of phospholipids. The sphingomyelin content of the phospholipid fraction of both membranes was higher than in these fractions from other cell components, β-carotene, a constituent characteristic of milk fat, was present in the lipid fraction of the plasma membrane. Cholesterol esters of plasma membrane were similar in fatty acid composition to those of milk fat globule membranes. Disc electrophoresis of either membrane preparation on polyacrylamide gels revealed a single major protein component characteristic of plasma membrane from other sources. Distinct morphological differences between plasma membrane and milk fat globule membranes were observed in both thin sections and in negatively stained material. Plasma membrane was vesicular in appearance while milk fat globule membranes had a platelike aspect. These observations are consistent with derivation of fat globule membrane from plasma membrane accompanied by structural rearrangement of membrane constituents.     

类囊体膜的垛叠、松散与它的功能关系

菠菜完整叶绿体置于4mM MgCl_2或20 mM KCl低浓度介质中低渗10秒钟后,得到由Mg~(++)或K~+离子诱导的类囊体垛叠膜和松散膜。它们在功能上表现出明显的差异。垛叠膜有较高的毫秒级延迟光发射(ms-DLE),松散膜显著降低DLE的快相,垛叠膜比松散膜的9-AA荧光猝灭快,并保持稳定;而松散膜有H~+渗漏。在非循环或Fd催化的循环光合磷酸化中,垛叠膜比松散膜活力高。但是,若在同样的低渗介质中低渗1分钟以上,Mg~(++)离子诱导的垛叠膜,在显微结构上不同于低渗过10秒钟的垛叠膜,它垛叠较松,而且在磷酸化活力上也与松散膜差别不大。揭示了H~+传递速度受二个光系统、电子载体间的距离及偶联程度的限制。新鲜制备的垛叠或松散膜,在NADP~+还原系统中,具有相同的电子传递放O_2速度,说明电子传递速度在一定范围内不受膜间的距离和偶联程度的影响。但是松散膜不稳定,随着膜的老化而解联,牛血清白蛋白(BSA)能稳定松散膜的电子传递。     

BIOCHEMICAL AND ULTRASTRUCTURAL PROPERTIES OF A MITOCHONDRIAL INNER MEMBRANE FRACTION DEFICIENT IN OUTER MEMBRANE AND MATRIX ACTIVITIES

Treatment of the inner membrane matrix fraction of rat liver mitochondria with the nonionic detergent Lubrol WX solubilized about 70% of the total protein and 90% or more of the following matrix activities: malate dehydrogenase, glutamate dehydrogenase, and isocitrate dehydrogenase (NADP). The Lubrol-insoluble fraction was enriched in cytochromes, phospholipids, and a Mg⁺⁺-stimulated ATPase activity. Less than 2% of the total mitochondrial activity of monoamine oxidase, an outer membrane marker, or adenylate kinase, an intracristal space marker could be detected in this inner membrane fraction. Electron micrographs of negatively stained preparations showed vesicles (≤0.4 µ diameter) literally saturated on the periphery with the 90 A ATPase particles. These inner membrane vesicles, which appeared for the most part to be inverted with respect to the normal inner membrane configuration in intact mitochondria, retained the succinicoxidase portion of the electron-transport chain, an intact phosphorylation site II with a high affinity for ADP, and the capacity to accumulate Ca⁺⁺. A number of biochemical properties characteristic of intact mitochondria and the inner membrane matrix fraction, however, were either absent or markedly deficient in the inner membrane vesicles. These included stimulation of respiration by either ADP or 2,4-dinitrophenol, oligomycin-sensitive ADP-ATP exchange activity, atractyloside sensitivity of adenine nucleotide requiring reactions, and a stimulation of the Mg⁺⁺-ATPase by 2,4-dinitrophenol.     

人红细胞膜和血浆游离脂肪酸成分分析及其对膜微粘度的影响

采用高效液相色谱（ＨＰＬＣ）和荧光偏振技术测定了４２例正常人红细胞膜和血浆游离脂肪酸（ＦＦＡ）及膜微粘度,并探讨了膜脂肪酸和血浆ＦＦＡ构成与膜微粘度之间的关系。结果表明：正常人红细胞膜主要由廿二碳六烯酸（Ｃ２２∶６）、花生四烯酸（Ｃ２０∶４）、亚油酸（Ｃ１８∶２）、软脂酸（Ｃ１６∶０）、油酸（Ｃ１８∶１）和硬脂酸（Ｃ１８∶０）等六种脂肪酸组成。血浆ＦＦＡ构成与膜脂肪酸相似,但不含Ｃ２２∶６而含十四烷酸（Ｃ１４∶０）。红细胞膜各脂肪酸含量大多与其血浆浓度呈明显正相关。红细胞膜微粘度与膜软脂酸和硬脂酸呈明显正相关,与膜廿二碳六烯酸和花生四烯酸呈明显负相关。提示红细胞膜脂肪酸组成受血浆ＦＦＡ成分影响;而红细胞膜脂肪酸成分对膜微粘度亦有重要影响     

MEMBRANE POTENTIALS AND CATAPHORETIC POTENTIALS OF PROTEINS

1. It has been shown in preceding publications that the membrane potentials of protein solutions or gels are determined by differences in the concentration of a common ion (e.g. hydrogen ion) inside a protein solution or protein gel and an outside aqueous solution free from protein, and that the membrane potentials can be calculated with a good degree of accuracy from Donnan''s equation for membrane equilibria. 2. On the basis of the theory of electrical double layers developed by Helmholtz, we are forced to assume that the cataphoretic potentials of protein particles are determined by a difference in the concentration of the two oppositely charged ions of the same electrolyte in the two strata of an electrical double layer surrounding the protein particle but situated entirely in the aqueous solution. 3. The membrane potentials of proteins agree with the cataphoretic potentials in that the sign of charge of the protein is negative on the alkaline side and positive on the acid side of the isoelectric point of the protein in both membrane potentials and cataphoretic potentials. The two types of potential of proteins disagree, especially in regard to the action of salts with trivalent and tetravalent ions on the sign of charge of the protein. While low concentrations of these salts bring about a reversal of the sign of the cataphoretic potentials of protein particles (at least in the neighborhood of the isoelectric point), the same salts can bring the membrane potentials of proteins only to zero, but call bring about no or practically no reversal of the sign of charge of the protein. Where salts seem to bring about a reversal in the membrane potential of protein solutions, the reversal is probably in reality always due to a change in the pH. 4. We may state, as a result of our experiments, that the cataphoretic migration and the cataphoretic P.D. of protein particles or of suspended particles coated with a protein are the result of two groups of forces; namely, first, forces inherent in the protein particles (these forces being linked with the membrane equilibrium between protein particles and the outside aqueous solution); and second, forces inherent entirely in the aqueous solution surrounding the protein particles. The forces inherent in the protein particles and linked with the membrane equilibrium prevail to such an extent over the forces inherent in the water, that the sense of the cataphoretic migration of protein particles is determined by the forces resulting from the membrane equilibrium.     

能化态与线粒体及其内膜体膜表面局部脱水

荧光探针ＤＰＥ（Ｄｉｐａｌｍｉｔｏｙｌ－Ｎ－ＤａｎｓｙｌＰｈｏｓｐｈａｔｉｄｙｌｅｔｈａｎｏｌａｍｉｎｅ）标记于鼠肝线粒体及其内膜体膜表面,以测定其膜表面介电常数（ε）的变化与膜能化态的关系．在含有鱼藤酮的线粒体或其内膜体悬液中,加入琥珀酸,使膜处于能化态,可使膜表面。值分别下降１１％和２０％,分别再加ＫＣＮ,ＣＣＣＰ或Ｎｉｇｅｒｉｃｉｎ均能使ε值回升９％;若在上述悬液中,先加ＫＣＮ或ＣＣＣＰ,然后加入琥珀酸,则膜表面ε值无变化。若在线粒体或其内膜体悬液中,先加入ＣＣＣＰ或Ｎｉｇｅｒｉｃｉｎ,两者可使膜表面ε值升高１２％,其后加入鱼藤酮或琥珀酸等,则ε值均无变化,说明呼吸链抑制剂或解偶联剂抑制或解除膜的能化态,均可使膜表面ε值不发生变化。在另一组实验中,先加ＫＣＮ后,再加ＡＴｈ,使线粒体内膜处于能化态,表面ε值下降８％,此时再加寡霉素,则膜表面ε值相反上升１０％。这些实验事实均证明,线粒体膜处于能化态时,ε值下降,解除给化态,使ε值又上升。为能化态与线粒体膜表面水化力下降的相互关系提供了新信息．也为质子泵引起膜表面质子化,进而引起表面脱水,驱动膜融合的理论模型提供了新的证据。     

THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR : VI. THE PROTAMINE-COLLODION MEMBRANE,A NEW ELECTROPOSITIVE MEMBRANE

1. Strongly electropositive porous membranes were prepared by the adsorption of protamine (salmine) on porous collodion membranes. These membranes retain their electrochemical chracteristics for at least 12 months without change. 2. They are distinctly electropositive between pH 1 and 10, the range of most pronounced electropositive behavior occurring in solutions between pH 3 and pH 8. The filtration rates and ohmic resistance of these membranes do not differ significantly from similar uncoated membranes. 3. The porous protamine-collodion membranes show very pronounced positive anomalous osmosis, the observed effects with proper electrolytes being similar to those obtained with oxidized collodion membranes. They also show very conspicuous negative osmosis with strong acids. 4. Protamine-collodion membranes which correspond in their properties to the activated dried collodion membranes were prepared by the adsorption of protamine on porous collodion membranes followed by drying in air. The concentration potentials across such dried protamine-collodion membranes closely approach the thermodynamically possible maximum.     

伴刀豆球蛋白A与巨噬细胞膜上受体作用下膜变形性及细胞吞噬能力变化

本文采用图像分析、相差显微、生物活性测定等技术,研究ConA与巨噬细胞膜受体结合后对细胞行为与功能的影响. ConA与受体结合后巨噬细胞膜面积增大、变形性和吞噬能力增强、细胞产热量增加,表明细胞膜结构与功能发生变化.本实验是将图像分析技术用来研究相对图像采集速度要慢得多的活细胞特性的一次成功尝试.     

呼吸链底物和抑制剂对线粒体内膜流动性的影响

用DPH和ANS标记大鼠肝线粒体内膜,以稳态荧光偏振法,研究了呼吸链底物和抑制剂对内膜流动性的影响。1.苹果酸+谷氨酸、琥珀酸分别为底物,均能引起内膜流动性增加。2.琥珀酸对含心磷脂的脂质体的膜流动性无影响。3.在鱼藤酮存在的条件下,苹果酸+谷氨酸对内膜流动性的增加作用消失,但琥珀酸的作用仍然存在。有氰化钾时则琥珀酸的作用消失。4.不论外加底物存在与否,鱼藤酮使内膜的流动性下降,而氰化钾则使之增加。抗霉素A亦可使内膜的流动性增加。上述结果表明:线粒体内膜流动性与其功能密切相关。电子沿呼吸链传递使线粒体内膜流动性增加,这种变化可能与呼吸链成分的氧化还原态有关。     

杀菌肽及膜蛋白螺旋结构预测

杀菌肽是昆虫免疫系统的能够杀死细菌的一类重要的多肽。实验方法测蛋白质的二级结构很困难,汇集已有的八种预测螺旋结构的方法,通过计算机实现,对比杀菌肽、光合反应中心的预测结果和实验结果,推测了杀菌肽的作用机理．     

铁缺乏及运动对大鼠红细胞膜圆二色谱、膜表面电荷及膜流动性的影响

采用圆二色谱、膜表面电荷及膜流动性指标测定了铁缺乏和运动大鼠红细胞膜的损伤变化。发现铁缺乏和运动两因素同时存在时红细胞膜蛋白的α－螺旋含量显著偏高,边缘缺铁运动组偏低。运动使红细胞膜表面电荷显著下降。反映膜脂质流动性的,值各实验组差异不显著。提示缺铁和运动所致膜损伤与膜蛋白氧化修饰或膜蛋白成分增减有关。     

亲和素蛋白与含有生物素的支撑平面膜之间相互作用的研究

生物功能分子的二维有序化组装是分子工程学的重要内容。本文通过构建有生物素受体的人工模型膜,对亲和素与生物素这一具有极强亲和力的系统之间的特异性相互作用的某些制约因素进行了探讨．应用ＬＢ膜技术结合激先椭圆偏振术和表面等离激元谱技术,较深入地研究了蛋白质与脂单层膜发生的非特异性吸附,特异性结合以及结合的侧向空间位阻效应．实验结果表明,膜表面电荷对非特异性吸附的速率有很大的影响,而对最终的蛋白吸附量影响不大;非特异性的吸附可以通过二阶阳离子的脱附而去除;受体蛋白质与配体间的特异性结合受到侧向空间位阻效应的制约．