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131.
脱落酸对线粒体Na^+—K^+ATPase活性的影响 总被引:3,自引:0,他引:3
在提取大豆(Glycine m ax)黄化子叶的线粒体时,于清洗和悬浮介质中加入ABA,发现40 μm ol/L(±) ABA 对线粒体膜结合Na+ -K+ ATPase 活性及线粒体吸氧速率有明显的促进作用。ABA 可使16℃与27℃培养的大豆子叶线粒体膜结合Na+ -K+ ATPase Arrhenius图的折点温度分别下降6.3℃和5.9℃,并将该酶的底物动力学曲线由正协同曲线转变为非协同曲线。表明ABA 可降低线粒体的膜相变温度 相似文献
132.
D. C. Swartzendruber A. Manganaro K. C. Madison M. Kremer P. W. Wertz C. A. Squier 《Cell and tissue research》1995,279(2):271-276
Previous studies have demonstrated that the intercellular spaces of the stratum corneum contain multilamellar lipid sheets with variable ultrastructure in addition to desmosomes or desmosomal remnants. The intercellular lamellae are thought to provide a permeability barrier whereas the desmosomes are responsible for cell-cell cohesion. In this study, transmission electron microscopy of RuO4-fixed tissue was used to compare the proportions of the intercellular spaces in epidermal and palatal stratum corneum occupied by desmosomes and by different patterns of lamellae. Desmosomes are more abundant in palatal than in epidermal stratum corneum (46.9 vs 15.0% length of intercellular space). In epidermis the most frequent lamellar arrangements involve 3 (23.5%) or 6 (24.2%) lucent bands with an alternating broad-narrow-broad pattern, whereas the most frequent lamellar arrangements in palatal tissue are 2 (17.2%) or 4 (10.5%) lucent bands of uniform width. Most of the nondesmosomal portion of the intercellular space in palatal stratum corneum was dilated and had elongated lamellae at the periphery and short disorganized lamellae and amorphous electron-dense material in the interior. It is concluded that the multilamellar lipid sheets are less extensive in palatal than in epidermal stratum corneum, which could explain the greater permeability of the palate. 相似文献
133.
M. J. Katkowska 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1995,177(4):519-526
The membrane potential of ventral longitudinal muscles of Tenebrio molitor larvae was studied as a function of time and of cesium substituted for all or part of external potassium. The conventional microelectrode technique was applied. The mean value of resting potential was — 47.4 mV in standard physiological saline which did not change significantly with time (90 min). Cesium caused, almost immediately, a significant hyperpolarization of membrane potential the magnitude of which depended on cesium concentration. The presence of external potassium enhanced the effectiveness of cesium action, resulting in more pronounced hyperpolarization. The effect of Cs ions was fully reversible upon washing. These data support the idea that inward potassium current can be activated at resting potential level, at least in some cells, including the muscles studied. It is presumed that this potassium current might have some contribution to the resting membrane potential generation in mealworm larva muscles.Abbreviations [K
+]0
extracellular concentration of K ions
-
E
m
resting membrane potential of a cell when bathed in normal saline
-
E
K
K
+
equilibrium potential
-
MP
membrane potential
-
RP
resting potential
-
SD
standard deviation
-
SEM
standard error of the mean 相似文献
134.
脱落酸对植物线粒体膜生物物理特性的影响 总被引:3,自引:1,他引:2
采用1,6-二苯基-1,3,5-已三乙烯(DPH)荧光偏振法和中性红法分别研究了脱落酸(ABA)对玉米黄化芽及大豆子叶离体线粒体膜的微粘度(η)、表面电位(ψ)等生物物理特性的影响。结果表明:ABA有降低线粒体膜的微粘度及提高线粒体膜的表面电位作用,并导致呼吸速率升高,呼吸控制和氧化磷酸化偶联下降。ABA对线粒体膜微粘度的作用具有浓度饱和效应;ABA对线粒体膜表面电位的提高作用,因植物不同而有差异,对玉米的作用要大于对大豆的。追踪线粒体A(350)值的变化,还证实,ABA提高了大豆线粒体的A(350)值,即导致大豆线粒体的相互聚集(aggregation)。 相似文献
135.
A.G. MacDonald 《生物化学与生物物理学报:生物膜》1984,775(2):141-149
Tetrahymena was grown at up to 260 atm to see if the bilayer-ordering effect of pressure increased the proportion of unsaturated fatty acids in the membrane lipids. Both whole cells and microsomes showed no such change in their fatty acid composition. The most striking effect was seen in the former which showed a pressure-dependent increase in the proportion of C16:0 in relation to C16:Δ9. Homeoviscous adaptation to pressure does not appear to occur in this cell. 相似文献
136.
4,4′-Diisothiocyano-1,2-diphenylethane-2,2′-disulfonic acid (H2DIDS) known as an irreversible inhibitor of the anion transport in red blood cells (Cabantchik, Z.I. and Rothstein, A. (1972) J. Membrane Biol. 10, 311–330) blocks also the uptake of bile acids and of some foreign substrates in isolated hepatocytes (Petzinger, E. and Frimmer, M. (1980) Arch. Toxicol. 44, 127–135). [3H]H2DIDS was used for labeling of membrane proteins probably involved in anion transport of rat liver cells. The membrane proteins modified in vitro by [3H]H2DIDS were compared with those labeled by brominated taurodehydrocholic acid. The latter is one of a series of suitable taurocholate derivatives, all able to bind to defined membrane proteins of hepatocytes and also known to block the uptake of bile acids as well as of phallotoxins and of cholecystographic agents (Ziegler, K., Frimmer, M., Möller, W. and Fasold, H. (1982) Naunyn-Schmiedeberg's Arch. Pharmacol. 319, 254–261). The radiolabeled proteins were compared after SDS-electrophoresis with and without reducing agent present, solubilization by detergents, two-dimensional electrophoresis and after separation of integral and peripheral proteins. Our results suggest that the anion transport system of liver cells cannot distinguish between bile acids and the anionic stilbene derivative (DIDS). The labeling pattern for both kinds of affinity labels was very similar. Various combinations of separation techniques gave evidence that the radiolabeled membrane proteins are not subunits of a single native channel protein. 相似文献
137.
Vsevolod A. Tverdislov Salam El Karadaghi Doris J. Bucher Juri A. Zakomirdin Igor G. Kharitonenkov 《生物化学与生物物理学报:生物膜》1984,778(2):276-280
The dependence of the surface potential difference (ΔU), transversal elasticity module (E1) and membrane conductivity (G0) on the concentrations of the antiviral drugs, rimantadine and amantadine was studied in the planar bilayer lipid membrane system. The method used was based on independent measurements of the second and third harmonics of the membrane capacitance current. The binding constants of bilayer lipid membranes obtained from the drug adsorption isotherms were 2.1 · 105 M?1 and 1.3 · 104 M?1 for rimantadine and amantadine, respectively. The changes in G0 took place only after drug adsorption saturation had been achieved. The influence of rimantadine and amantadine on the interaction of bilayer lipid membranes with matrix protein from influenza virus was also investigated. The presence of 70 μg/ml rimantadine in the bathing solution resulted in an increase in the concentration of M-protein at which the adsorption and conductance changes were observed. The effects of amantadine were similar to those of rimantadine but required a higher critical concentration of amantadine. The results obtained suggest that the antiviral properties of rimantadine and amantadine may be related to the interaction of these drugs with the cell membrane, which can affect virus penetration into the cell as well as maturation of the viral particle at the cell membrane. 相似文献
138.
Michael J. Barber Andrew S. Zektzer Gerald M. Rosen Helen A. Demos Elmer J. Rauckman 《生物化学与生物物理学报:生物膜》1984,776(1):159-168
Hepatic microsomal membranes, prepared under various conditions that yield either ‘intact’ or ‘disrupted’ microsomal vesicles, have been labeled via the sulfhydryl groups of intrinsic membrane proteins using nitroxide analogs of . Electron paramagnetic resonance spectra revealed the presence of two dominant classes of bound label corresponding to differing degrees of immobilization, the ratio of which were quantitated using a parameter designated the ‘’ ratio. For latent microsomes, the value of this parameter was determined to be and was influenced by factors such as label/protein ratio, incubation period, nitroxide structure, temperature and pH. The ratio was also sensitive to the degree of membrane integrity as revealed by the latency of mannose 6-phosphate activity of glucose-6-phosphohydrolase. In addition, membrane disruption resulted in a corresponding decrease in the order parameter for nitroxide-labeled fatty acids intercalated within the lipid bilayer. The ratio was observed to be dependent upon the method of microsome preparation yielding values of for ‘hypertonically disrupted’ vesicles and for ‘mechanically disrupted’ vesicles. Microsomal marker enzymes such as cytochrome and FAD-containing monooxygenase retained significant levels of functionally following nitroxide incorporation. 相似文献
139.
Antibodies were raised in rabbits against the outer membrane of Neurospora mitochondria. Antibodies were obtained that were specific for this membrane's major polypeptide () and its slower-migrating derivatives on SDS-polyacrylamide gels. These antibodies inhibited the insertion into phospholipid bilayers of voltage-dependent ion channels from detergent extracts of the mitochondrial outer membranes. The same antibodies bound preferentially to membranes containing crystalline surface arrays in outer mitochondrial membrane fractions. These results indicate that the 31 kDa polypeptide is a component both of the ion channels and of the membrane arrays, suggesting identity between the functional and structural entities. 相似文献
140.
The dielectric dispersion of isolated intact mitochondria in suspension has been measured between 10 kHz and 500 MHz. In isotonic KCI media at 4°C, the mitochondria maintained their characteristic ‘double membrane’ structure as examined by electron microscopy, and the observed dispersion curves were successfully simulated in terms of a superposition of two sub-dispersions having different characteristic frequencies and different permittivity magnitudes. Taking these observations into account we analyzed the dispersion data on the basis of a ‘double-shell’ model in which two concentric shells are meant to represent the mitochondrial outer and inner membranes. The analyses by a computerized curve-fitting method revealed that: (i) electric capacities for the outer and the inner membrane are 1.7 and 0.5 μF/cm2, respectively, (ii) relative permittivity for the inner compartment (or the equivalent homogeneous matrical space) = 50–60, (iii) outer compartment-to-external conductivity ratio = 0.4–0.6, and (iv) inner compartment-to-external conductivity ratio = 0.14. The implications of these parameter values are discussed with due attention paid to the limitations inherent in our ‘double-shell’ model approach. 相似文献