Energy landscape of the reactions governing the Na + deeply occluded state of the Na + /K + -ATPase in the giant axon of the Humboldt squid
| العنوان: | Energy landscape of the reactions governing the Na + deeply occluded state of the Na + /K + -ATPase in the giant axon of the Humboldt squid |
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| المؤلفون: | Miguel Holmgren, Francisco Bezanilla, Joshua J. C. Rosenthal, Daniel Basilio, Daniela De Giorgis, Juan P. Castillo, David C. Gadsby, Ramon Latorre |
| المصدر: | PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Artículos CONICYT CONICYT Chile instacron:CONICYT |
| بيانات النشر: | Proceedings of the National Academy of Sciences, 2011. |
| سنة النشر: | 2011 |
| مصطلحات موضوعية: | Sodium-Potassium-Exchanging ATPase, Enthalpy, Ion, Diffusion, Adenosine Triphosphate, Ion binding, ATP hydrolysis, Animals, Na+/K+-ATPase, Ions, Multidisciplinary, Chemistry, Hydrolysis, Sodium, Decapodiformes, Temperature, Giant axon, Energy landscape, Biological Sciences, Axons, Electrophysiology, Kinetics, Biochemistry, Biophysics, Thermodynamics, Protein Binding |
| الوصف: | The Na + /K + pump is a nearly ubiquitous membrane protein in animal cells that uses the free energy of ATP hydrolysis to alternatively export 3Na + from the cell and import 2K + per cycle. This exchange of ions produces a steady-state outwardly directed current, which is proportional in magnitude to the turnover rate. Under certain ionic conditions, a sudden voltage jump generates temporally distinct transient currents mediated by the Na + /K + pump that represent the kinetics of extracellular Na + binding/release and Na + occlusion/deocclusion transitions. For many years, these events have escaped a proper thermodynamic treatment due to the relatively small electrical signal. Here, taking the advantages offered by the large diameter of the axons from the squid Dosidicus gigas , we have been able to separate the kinetic components of the transient currents in an extended temperature range and thus characterize the energetic landscape of the pump cycle and those transitions associated with the extracellular release of the first Na + from the deeply occluded state. Occlusion/deocclusion transition involves large changes in enthalpy and entropy as the ion is exposed to the external milieu for release. Binding/unbinding is substantially less costly, yet larger than predicted for the energetic cost of an ion diffusing through a permeation pathway, which suggests that ion binding/unbinding must involve amino acid side-chain rearrangements at the site. |
| تدمد: | 1091-6490 0027-8424 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::4abeccc39239a9a67a0e776c0346f9db https://doi.org/10.1073/pnas.1116439108 |
| حقوق: | OPEN |
| رقم الأكسشن: | edsair.doi.dedup.....4abeccc39239a9a67a0e776c0346f9db |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 10916490 00278424 |
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