Lateral Electron Transport Research Articles

Lateral Diffusion as a Rate-limiting Step in Ubiquinone-mediated Mitochondrial Electron Transport

Data are presented which indicate that the diffusion-based collisions of ubiquinone with its redox partners in the mitochondrial inner membrane are a rate-limiting step for maximum (uncoupled) rates of succinate-linked electron transport. Data were obtained from experimental analysis of a comparison of the apparent activation energies of lateral diffusion rates, collision frequencies, and electron transport rates in native and protein-diluted (phospholipid-enriched) inner membranes. Diffusion coefficients for Complex III (ubiquinol:cytochrome c oxidoreductase) and ubiquinone redox components were determined as a function of temperature using fluorescence recovery after photobleaching, and collision frequencies of appropriate redox partners were subsequently calculated. The data reveal that 1) the apparent activation energies for both diffusion and electron transport were highest in the native inner membrane and decreased with decreasing protein density, 2) the apparent activation energy for the diffusion step of ubiquinone made up the most significant portion of the activation energy for the overall kinetic activity, i.e. electron transport steps plus the diffusion steps, 3) the apparent activation energies for both diffusion and electron transport decreased in a proportionate manner as the membrane protein density was decreased, and 4) Arrhenius plots of the ratio of experimental electron transport productive collisions (turnovers) to calculated theoretically predicted, diffusion-based collisions for ubiquinone with its redox partners had little or no temperature dependence, indicating that as temperature increases, increases in electron transport rate are accounted for by the increases in diffusion-based collisions. These data support the Random Collision Model of mitochondrial electron transport in which the rates of diffusion and appropriate concentrations of redox components limit the maximum rates of electron transport in the inner membrane.

Electrochemistry at the water/air interface. Lateral electron transport in Langmuir monolayers

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrochemistry at the water/air interface. Lateral electron transport in Langmuir monolayersCindra A. Widrig, Cary J. Miller, and Marcin. MajdaCite this: J. Am. Chem. Soc. 1988, 110, 6, 2009–2011Publication Date (Print):March 1, 1988Publication History Published online1 May 2002Published inissue 1 March 1988https://doi.org/10.1021/ja00214a080RIGHTS & PERMISSIONSArticle Views122Altmetric-Citations26LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (389 KB) Get e-Alerts Get e-Alerts

ChemInform Abstract: Microporous Aluminum Oxide Films at Electrodes; Part 3. Lateral Electron Transport in Self‐Assembled Monolayers of N‐Methyl‐N′‐octadecyl‐4,4′‐bipyridinium Chloride.

AbstractThe direct electrochemical measurement of lateral electron transport in an amphiphilic monolayer consisting of (I) and (II) is reported.

Choice of optimum megavoltage for accelerators for photon beam treatment

Over three decades ago, the development of megavoltage accelerators revolutionized radiation oncology and provided the therapist with photons and electrons of any desired energy. The initial advantages cited for high energy photon therapy, listed below, have proved valid and accelerators have almost totally replaced orthovoltage units. Initially, it appeared that most of these cited advantages should continue to improve with increasing energy, and there has been an impetus for the production of ever higher megavoltage accelerators. Some of these advantages are reviewed in this paper. Also. recent investigations have indicated increasing diffuseness of the photon beam boundary with increasing energy because of lateral transport of electrons. The impact on treatment planning as a function of energy of the increase in volume dose due to the diffuseness of beam boundaries, “build-down” and “rebuild-up” effects in tissues at cavity and inhomogeneity interfaces, bone absorption, and photoneutron production are discussed. Consideration of the behavior of these parameters indicates that optimum photon energies have been achieved and that the impetus for higher megavoltages is unwarranted for most treatment. For many therapeutic applications, there are major advantages of 4 MV to 8 MV photon beams relative to 60Co gamma rays. For large lesions in the abdomen or pelvis there is an advantage to energies above those provided by 15 MV units. The various considerations above are discussed and summarized as a function of lesion site and megavoltage.

Microporous aluminum oxide films at electrodes. 3. Lateral electron transport in self-assembled monolayers of N-methyl-N'-octadecyl-4,4'-bipyridinium chloride

Donnees sur les mesures electrochimiques du transfert d'electrons lateral dans un ensemble de couches monomoleculaires de chlorure de N-methyl-N'octadecyl-bipyridinium-4,4' sur des films d'alumine poreuse, sur des electrodes d'or

Uniformity and isotropy of the fast ion emission at a target surface irradiated by a CO2 laser

Filtered pinhole imaging is used to characterize spatially the fast ion emission at the target surface irradiated by a CO2 laser in a planar geometry. The bulk of the fast ions is found to be fairly well correlated with the lateral transport of hot electrons in the target plane, i.e., a large concentration of rather low-energy ions near the focal spot with total ion emission over a very large area. Higher-energy ions show large emission nonuniformities and very small local cone angles somewhat difficult to explain.

Lateral transport of hot electrons on a spherical target by 10.6-μm CO2 laser irradiation

Lateral transport of hot electrons on a spherical target irradiated with two beams of CO2 laser (4.8×1014 W/cm2) is studied by spatially resolved Kα x-ray measurements. The hot-electron energy and spatial distribution in the target are found to depend on the method of irradiation: tight and overlapped focusing conditions.

Electron mobilities in modulation-doped GaAs-(AlGa)As heterostructures

A brief review of lateral electronic transport in modulation-doped (AlGa)As-GaAs heterostructures, where mobilities can exceed 10 6 cm 2/V· s, is presented. Importance, strength and temperature dependence of the remaining electron scattering mechanisms are discussed.