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11.
SODIUM TRANSPORT IN ENTEROMORPHA INTESTINALIS (L.) LINK 总被引:1,自引:1,他引:0
12.
Gabriella Goldberg Daria Mochly-Rosen Sara Fuchs Yoram Lass 《The Journal of membrane biology》1983,76(2):123-128
Summary Monoclonal antibodies directed against the cholinergic binding site of the acetylcholine receptor were found to alter the ion channel properties in cultured chick myoballs. Time and dose dependent reduction in acetylcholine sensitivity was observed. Noise analysis experiments indicated a decrease in the mean single channel conductance and an increase in the mean single channel open time. 相似文献
13.
Alexander A. Bulychev Tijmen van Voorthuysen Wim J. Vredenberg 《Physiologia plantarum》1996,98(2):605-611
Electrochemical data obtained with TMPD+ -sensitive electrodes indicate that ammonium-uncoupled chloroplasts retain TMPD (N,N,N',N'-tetramethyl- p -phenylenediamine) mainly in the reduced form during illumination, whereas uncoupled DCMU-treated chloroplasts accumulate TMPD in the oxidized form (TMPD+ ). This observation indicates that the reduced plastoquinol is the preferred electron donor for photosystem I (PSI) and TMPD can only compete efficiently when plastoquinone reduction is blocked. After adding DCMU the formation of a transmembrane gradient for TMPD+ is reflected by a slow-down of the electrogenic electron transport and by the emerging of the overshoot of the membrane current in the light-off response. A light-dependent increase in photoelectric current generated by chloroplasts in the presence of NH4 Cl and TMPD is observed and considered to be caused by a reversible release of current limitation in the interfacial conductance barriers in the lumen. 相似文献
14.
Mengyi Ba Ruonan Chen Qiuchen Huang Yanli Song Wen Li Yuanyuan Zhang Haixin Liu Xiang Xu Weidong Zhang Zhiqiang Cai Tao Sun 《化学与生物多样性》2023,20(8):e202300350
This work firstly reported a new polycaprolactone based material functionalized with guanidinium ionic liquid (PCL-GIL) as the stationary phase with high resolution performance for capillary gas chromatography (GC). It is composed of polycaprolactone (PCL) and guanidinium ionic liquid (GIL) with amphiphilic conformation. The PCL-GIL capillary column coated by static method exhibited high column efficiency of 3942 plates/m and moderate polarity. As a result, the PCL-GIL column exhibited high-resolution capability. For a mixture of 27 analytes with a wide ranging polarity and outperformed the PCL-2OH and HP-35 columns, showing its advantageous separation capability for analytes of diverse types. Moreover, the PCL-GIL column showed high resolving capability for various positional isomers and cis-/trans-isomers, including alkylbenzenes, chlorobenzenes, naphthalenes, bromonitrobenzenes, chloronitrobenzenes, benzaldehydes, phenols, alcohols, respectively. In a word, PCL derivatized by GIL units as a new type of stationary phase has a promising future in GC separations. 相似文献
15.
Piotr Orlewski Vassilios Tsikaris Maria Sakarellos-Daitsiotis Constantinos Sakarellos Ketty P. Soteriadou Michel Marraud Manh Thong Cung 《Letters in Peptide Science》1996,3(5):317-326
Summary The IASRYDQL synthetic octapeptide (250–257) of the Leishmania major surface glycoprotein gp63 efficiently inhibits parasite attachment to the macrophage receptors in in vitro experiments, and the SRYD-containing tetrapeptide mimics antigenically and functionally the RGDS sequence of fibronectin. The conformational properties of the octapeptide were investigated in dimethylsulfoxide (DMSO) with the combined use of NMR data (vicinal coupling constants, nuclear Overhauser effects (NOEs) and temperature coefficient values), molecular modeling by energy minimization and molecular dynamics. The structure is characterized by the high occurrence, exceeding 95%, of the Arg-Asp side-chain-side-chain ionic interaction, which plays a key role in the backbone folding through a distorted type-I -turn involving the Gln256-NH to Arg253-CO hydrogen bond. 相似文献
16.
Malcolm N. Jones Philip Manley Angela Holt 《International journal of biological macromolecules》1984,6(2):65-68
The binding of sodium n-dodecyl sulphate to lysozyme has been measured by equilibrium dialysis at 25°C and pH 3.2 over a range of ionic strengts from 0.0119 to 0.2119. Binding isotherms in the region corresponding to ionic binding between the surfactant anions and cationic amino acid residues on the protein have been interpreted in terms of the Hill equation and exhibit positive cooperativity with Hill coefficients in the region of 7–11. The Gibbs energies of binding have been calculated from the Hill binding constants and from the Wyman binding potentials. The stability of the surfactant-protein complexes is discussed in relation to the stability of surfactant micelles. Ionic binding of the surfactant is weakened and hydrophobic binding strengthened by increasing ionic strength. 相似文献
17.
Raúl Alva J. Antonio Lugo-R Eduardo Arzt Jorge Cerbón Blanca E. Rivera Mireya Toro Sergio Estrada-O 《Journal of bioenergetics and biomembranes》1992,24(1):125-129
Nigericin is a monocarboxylic polyether molecule described as a mobile K+ ionophore unable to transport Li+ and Cs+ across natural or artificial membranes. This paper shows that the ion carrier molecule forms complexes of equivalent energy demands with Li+, Cs+, Na+, Rb+, and K+. This is in accordance with the similar values of the complex stability constants obtained from nigericin with the five alkali metal cations assayed. On the other hand, nigericinalkali metal cation binding isotherms show faster rates for Li+ and Cs+ than for Na+, K+, and Rb+, in conditions where the carboxylic proton does not dissociate. Furthermore, proton NMR spectra of nigericin-Li+ and nigericin-Cs+ complexes show wide broadenings, suggesting strong cation interaction with the ionophore; in contrast, the complexes with Na+, K+, and Rb+ show only clear-cut chemical shifts. These latter results support the view that nigericin forms highly stable complexes with Li+ and Cs+ and contribute to the explanation for the inability of this ionophore to transport the former cations in conditions where it catalyzes a fast transport of K+>Rb+>Na+.Part of the results of this paper were presented at the 14th International Congress of Biochemistry in Prague, Czechoslovakia. 相似文献
18.
A. Diez de los Rios N. E. DeRose W. McD Armstrong 《The Journal of membrane biology》1981,63(1-2):25-30
Summary Open-tip and liquid ion-exchanger microelectrodes were used to study the effects of cAMP (6mm, added to the serosal medium) on apical membrane potential (E
m
) and intracellular sodium, potassium, and chloride activities (a
Na
i
,a
K
i
,a
Cl
i
) inNecturus gallbladder under open-circuit conditions. Transepithelial potential difference (E
Tr
) was also measured. In the presence of cAMP,a
Cl
i
fell from about 1.5 times its equilibrium value to a level that corresponded to electrochemical equilibrium across the apical and basolateral cell membranes. Under these conditionsa
Na
i
decreased anda
K
i
increased,E
m
was unchanged andE
Tr
increased from virtually zero to a small but significant serosal positive value. The cAMP-induced increase ina
K
i
was abolished when Cl–-free incubation media were used. Addition of the Ca++-ionophore A23187 (0.5 g/ml) to the serosal medium had no effect onE
m
,E
Tr
, ora
Cl
i
. When A23187 was added to the mucosal medium,E
m
and the basolateral membrane potential hyperpolarized by about 20 mV and an increase in the outwardly directed electrochemical driving force for Cl– was observed. These results indicate that cAMP inhibits coupled transapical Na–Cl entry into epithelial cells ofNecturus gallbladder and suggest that this inhibition may not be mediated by an increase in intracellular Ca++ concentration. 相似文献
19.
Claude E. Boyd 《Hydrobiologia》1981,80(1):91-93
Ion-pairing has little effect on ionic activity calculations for weakly mineralized natural water (ionic strength < 2 mM). However, for more strongly mineralized freshwaters, corrections for ion-pairing are necessary if highly accurate ionic activities are required. 相似文献
20.
Nakita K. Noel Severin N. Habisreutinger Bernard Wenger Yen‐Hung Lin Fengyu Zhang Jay B. Patel Antoine Kahn Michael B. Johnston Henry J. Snaith 《Liver Transplantation》2020,10(4)
Halide perovskites are currently one of the most heavily researched emerging photovoltaic materials. Despite achieving remarkable power conversion efficiencies, perovskite solar cells have not yet achieved their full potential, with the interfaces between the perovskite and the charge‐selective layers being where most recombination losses occur. In this study, a fluorinated ionic liquid (IL) is employed to modify the perovskite/SnO2 interface. Using Kelvin probe and photoelectron spectroscopy measurements, it is shown that depositing the perovskite onto an IL‐treated substrate results in the crystallization of a perovskite film which has a more n‐type character, evidenced by a decrease of the work function and a shift of the Fermi level toward the conduction band. Photoluminescence spectroscopy and time‐resolved microwave conductivity are used to investigate the optoelectronic properties of the perovskite grown on neat and IL‐modified surfaces and it is found that the modified substrate yields a perovskite film which exhibits an order of magnitude lower trap density than the control. When incorporated into solar cells, this interface modification results in a reduction in the current–voltage hysteresis and an improvement in device performance, with the best performing devices achieving steady‐state PCEs exceeding 20%. 相似文献