带电磷脂膜泡的内、外表面电荷密度和表面电位

本文按Gouy-Chapman理论,推导了稳定条件下磷脂膜泡膜内、外表面电荷密度/表面电位关系和表面电位分布以及带电磷脂在膜泡内外两侧的不对称分布的近似表达式.并对这些表示式的极限情况和可能的应用进行了讨论,同时对带电磷脂在膜泡膜内、外两侧的不对称分布也作了讨论.     

THE ANTAGONISM BETWEEN SODIUM AND MAGNESIUM IONS IN THEIR ACTION UPON OXALATE ION

The action of NaCl upon the effect of MgCl₂ upon oxalate buffer systems, interpreted by Simms as an instance of antagonism of Na⁺ and Mg⁺⁺, has been shown to be capable of formulation as the effect of increasing ionic strength upon the dissociation of MgC₂O₄ into magnesium and oxalate ions.     

CHEMICAL ANTAGONISM OF IONS : II. ANTAGONISM BETWEEN ANIONS AND ALSO BETWEEN CATIONS AND ANIONS IN THEIR EFFECT ON OXALATE ACTIVITY.

Sulfate ions (SO₄ ⁼) produce an anomalous effect on the ionization of oxalate diion, opposite in direction to the effect of Mg⁺⁺ ions. This effect of sulfate is antagonized by the presence of Cl^- ions according to the equation: See PDF for Equation where f'' is the antilog of the increase in pK₂'' due to the sulfate. In solutions containing up to 0.03 molar MgSO₄ the effect of Mg⁺⁺ predominates over that of SO₄ ⁼. Above 0.1 molar the effect of SO₄ ⁼ predominates and tends to neutralize the initial deviation. In solutions containing fixed amounts of MgCl₂ and varying amounts of NaSO₄ (or vice versa) the effects of these two salts sharply antagonize each other in all proportions.     

细菌L型和一些肠道杆菌的电动力学研究

用电泳法研究了细菌Ｌ型及其亲代细菌型和一些肠道杆菌的电动力学特征。伤寒杆菌Ｌ型和葡萄球菌Ｃｏｗａｎ株Ｌ型的等电点与其亲代细菌型不同;普通大肠杆菌、普通变形杆菌的等电点与革兰氏阳性菌相似;白喉杆菌Ｌ型和葡萄球菌Ｗｏｏｄ株Ｌ型的等电点与其亲代细菌型无显著差异。电泳可使结晶紫染色的细菌脱去结晶紫,亦可使染色后经乙醇处理的普通大肠杆菌和伤寒杆菌脱色并在电场作用下泳动,但不能使染色后经乙醇处理的葡萄球菌脱色或泳动,痢疾杆菌、伤寒杆菌和肠道致病性大肠杆菌的等电点不同于普通大肠杆菌和普通变形杆菌;在一定ｐＨ范围内,电泳     

SURFACE CHARGE OF CHOLINE ACETYLTRANSFERASE FROM DIFFERENT SPECIES

—The adsorption of partially purified choline acetyltransferase (ChAc) from cat, rat, guinea-pig and pigeon brains by the cation exchange resins, CM-Sephadex (C-50) and Amberlite CG-50 II, was studied at various pH values and ionic strengths. ChAc from cat and rat were more strongly adsorbed by cation exchangers and therefore have a stronger net positive surface charge than those from guinea pig and pigeon. Experiments showed that the difference in adsorption between these two groups of enzymes could not be explained by overloading of the resin, by competitive effect of other proteins present in the enzyme preparations or by the presence of any component suppressing the adsorption of ChAc in any of the enzyme preparations. The adsorption of ChAc by a cation exchanger is very similar to its binding to synaptosome membranes. The significance of the positive surface charge of ChAc in studies on the compartmentation of ChAc in synaptosomes is discussed.     

THE SURFACE CHARGE OF RAT LIVER MITOCHONDRIA AND THEIR MEMBRANES : Clarification of Some Controversies Concerning Mitochondrial Structure

The surface charge of intact mitochondria and submitochondrial particles was examined by the technique of preparative free flow electrophoresis. When submitochondrial preparations obtained by a swelling-contraction procedure were examined with this technique, two fractions were observed. One of these fractions exhibited the same electrophoretic properties as intact mitochondria, which indicated that it was derived from the outer limiting membrane of the mitochondrion. This fraction was found to contain the enzymes monoamine oxidase and rotenone-insensitive NADH-cytochrome c reductase which have been reported to be localized in the outer mitochondrial membrane. The other fraction exhibited an electrophoretic mobility which was different from that of intact mitochondria, and this fraction contained enzymes characteristic of the inner membrane-matrix fraction such as soluble and particulate enzymes of the Krebs cycle. Microsomes exhibited an electrophoretic mobility which was almost identical with that of the outer mitochondrial membrane. In addition to resolving the localization of enzymes in mitochondrial membranes, these data indicate that the outer limiting membrane of the mitochondrion is the sole determinant of the surface charge of mitochondria.     

刀豆球蛋白A对Ehrlich腹水癌细胞的膜电位和表面电荷的影响

本文报告用荧光探剂diS-C_3—(5)和细胞电泳技术研究刀豆球蛋白A(ConA)作用于Ehrlich腹水癌细胞引起的膜电位和表面电荷的变化.ConA与细胞膜相应受体结合,导致在膜上的diS-C_3-(5)的荧光强度增加,表明细胞去极化.经用缬氨霉素诱导的钾扩散电位校正,与光学讯号变化相应的膜电位变化约是20mv.细胞经G毒毛旋化苷处理后,ConA引起的去极化程度比未处理过的细胞大.ConA作用于Ehrlich腹水癌细胞使细胞电泳迁移率变小.表明细胞表面负电荷数目减少.本文对这些变化的可能机制和相互关系进行了讨论.     

THE ANTAGONISM BETWEEN THYROID AND PARATHYROID GLANDS

From the facts stated in this paper it is evident that the thymus gland of mammals contains a substance which is capable of producing tetany when fed to the larvæ of certain species of salamanders (Ambystoma opacum and Ambystoma maculatum). As long as the larvæ have not developed their own thymus glands, they are able, by means of some mechanism, to counterbalance the tetanic action of the thymus substance introduced in their food. When, however, the secretion from their own thymus glands is added to the thymus material introduced with the food, this mechanism of preventing tetany becomes inadequate and tetany ensues. In the larva of a third species of salamander, Ambystoma tigrinum, this mechanism will prevent tetany even when the larvæ are fed on thymus. In mammals the parathyroids are known to prevent tetany and are supposed either to absorb the tetany-producing substance and thus prevent its action or to change it into another non-toxic substance. It is at least probable that in the amphibians the parathyroids play the same rôle. Larvæ of anuran amphibians, which develop their parathyroids soon after hatching, never show tetanic convulsions if they are fed on thymus, but in certain species of salamanders, whose parathyroids develop only during metamorphosis, the larvæ invariably have tetanic convulsions upon thymus feeding, while the metamorphosed animals never show tetany. But in addition to the parathyroids the salamanders must possess still another mechanism which during the larval period inhibits the production of tetany by the animal''s own thymus glands. In the larvæ of Ambystoma opacum and Ambystoma maculatum this mechanism is sufficient only to prevent tetany from the animal''s own thymus, while in the larvæ of Ambystoma tigrinum it is capable of preventing tetany even when the larvæ are fed with thymus. If the thymus is the organ by whose action tetany is produced, we can understand why tetany in human beings occurs far more frequently in children than in adults, since in the latter the thymus gland is replaced, at least to a great extent, by connective tissue. The relation of thymus to tetany may also possibly explain the occurrence of tetany during pregnancy; while the parathyroids of the mother may be sufficient to prevent tetany from her largely atrophied thymus, they may not be sufficient to prevent tetany from the excess of thymus substance furnished by the fetus to the blood of the mother.     

作用于钾离子通道蝎毒素的结构特征及活性表面研究进展

对作用于钾离子通道的蝎毒素的空间结构特点进行了简要归纳,发现高含量碱性残基在不同结构单元广泛分布而少量酸性残基特征性分布等新特点。蝎毒素活性表面研究进展表明,利用空间结构的分子模建结合残基突变是确定活性表面的有效方法。基于少量酸性残基特征分布与活性表面取向的相关性,提出酸性残基为活性调节残基的新观点和简单的“拇指”规则预测钾毒素活性表面的方法,从而可望加速蝎毒素的结构与功能关系研究。     

能量化时线粒体内膜表面电荷的变化

本文报告用荧光探剂1,8—ANS和电泳激光光散射技术,研究鼠肝线粒体内膜在加入ATP的能量化过程中其膜表面电荷的变化。实验结果表明在加入ATP后线粒体内膜的能量化使其膜表面的负电荷减少。作者论讨了用上述二种方法研究线粒体内膜在能量化时表面电荷变化的有关问题。     

SPACES,BARRIERS, AND ION CARRIERS: ION ABSORPTION BY PLANTS

Epstein , Emanuel . (U. California, Davis.) Spaces, barriers, and ion carriers: ion absorption by plants. Amer. Jour. Bot. 47(5) : 393—399. 1960.—Ions from the external medium initially invade “outer” or “free” spaces of plant cells and tissues, by diffusion and ion exchange. This process is essentially non-metabolic and non-selective, and is readily reversible. The spaces accessible in this manner seem to be confined to the cell walls. From here, ions are selectively transported into “inner” spaces separated from the “outer” space by diffusion barriers. Ion carriers accomplish the selective transfer of the ions across the barriers or membranes, first into the cytoplasm and thence into the vacuole. The second step, into the vacuole, can be by-passed by those ions moving into the xylem elements and up to the shoot, and some transport to the shoot may skirt the active transport mechanisms entirely.