Proton transport catalyzed by the nitrate-insensitive, vanadate-sensitive H+-ATPase in microsomes from maize (Zea mays L.) roots washed with 0.25 molar KI decreased as a function of time at 0 to 4°C. The rate of proton transport was approximately one-half of that by freshly isolated microsomes after 6 to 18 hours of cold storage. The decrease in proton transport coincided with losses in membran...

Synthesis and characterization of the novel sulfonated BAPPO monomer and its use in the synthesis of a new phosphine oxide-based sulfonated polyimide are described. BTDA, 6FDA, and DDS were used as monomers in the polyimide synthesis. Sulfonated polyimide membranes were obtained by a solution thermal imidization method. The thermal behavior of the polymers was investigated by DSC and TGA. The m...

Studies on proton and Na+ transport by isolated intestinal and renal brush-bordermembrane vesicles were carried out to test for the presence of an Na+/H+-exchange system. Proton transport was evaluated as proton transfer from the intravesicular space to the incubation medium by monitoring pH changes in the membrane suspension induced by sudden addition of cations. Na+ transport was determined a...

Proton exchange membranes (PEMs) play an important role in the fuel cell systems. A good PEM must meet a series of requirements such as high proton conductivity, excellent mechanical strength and stability, chemical and electrochemical stability, low fuel crossover, etc. Nafion is currently the most commercially utilized electrolyte membranes for polymer electrolyte fuel cells, with high chemic...

Proton exchange membranes were prepared by radiation-induced grafting of styrene onto commercial poly(tetrafluoroethylene-co-hexafluoropropylene) films using a simultaneous irradiation technique followed by a sulfonation reaction. The resulting membranes were characterized by measuring their physicochemical properties such as water uptake, ion exchange capacity, hydration number, and proton con...

Evidence has been gathering from several laboratories that protons in proton-pumping membranes move along or within the bilayer rather than exchange with the bulk phase. These experiments are typically conducted on the natural membrane in vivo or in vitro or on fragments of natural membrane. Anionic lipids are present in all proton-pumping membranes. Model studies on the protonation state of th...

The effect of palmitic acid (PA) and oleic acid (OA) on electrical parameters of planar membranes was studied. We found a substantial difference between the effects of PA and OA on proton transfer. PA induced a small increase in conductance, requiring a new technique for estimating proton-mediated currents across low-conductance planar bilayers in which an electrometer is used to measure the tr...

Hartree-Fock ab initio and density functional theory calculations suggest that intra- and intermolecular proton transfer between neutral and protonated triazole tautomers play a vital role in the observed dramatic proton conduction in triazole-based polymer electrolyte membranes.

Acid secretion and proton conductive pathways across primary human airway surface epithelial cultures were investigated with the pH stat method in Ussing chambers and by single cell patch clamping. Cultures showed a basal proton secretion of 0.17 +/- 0.04 micromol.h(-1).cm(-2), and mucosal pH equilibrated at 6.85 +/- 0.26. Addition of histamine or ATP to the mucosal medium increased proton secr...