The role of sodium ions in ATP formation by the sodium pump

1977 ◽  
Vol 198 (1131) ◽  
pp. 109-128 ◽  

A study has been made to characterize ATP synthesis from ADP and P 1 by the sodium pump with membranes isolated from rabbit kidney. Incorporation of 32 P 1 into ATP was measured. ATP was not formed in a one-step reaction. Synthesis was dependent upon two separate incuba­tions in which incorporation of P 1 into phosphoprotein was followed by transfer of phosphate to ADP. The experimental conditions for the first reaction were different from those for the second (phosphate transfer) reaction. The latter took place only when a high Na concentration (at least 0.5 M) was added. ATP formation was prevented by both K and ouabain. The sequence of reactions could be repeated after washing to remove Na ions, indicating that the driving force for the reactions could be regenerated. The dissipation of ionic gradients was not involved because the Lubrol-solubilized pump was also able to synthesize ATP. It was concluded that the energy for ATP synthesis was derived from specific and reversible interactions of Na ions with the pump. The reactions for ATP synthesis by the sodium pump have been summarized in the form of a cycle.

Author(s):  
Nalin J. Unakar

The increased number of lysosomes as well as the close approximation of lysosomes to the Golgi apparatus in tissue under variety of experimental conditions is commonly observed. These observations suggest Golgi involvement in lysosomal production. The role of the Golgi apparatus in the production of lysosomes in mouse liver was studied by electron microscopy of liver following toxic injury by CCI4.


2006 ◽  
pp. 20-37 ◽  
Author(s):  
M. Ershov

The economic growth, which is underway in Russia, raises new questions to be addressed. How to improve the quality of growth, increasing the role of new competitive sectors and transforming them into the driving force of growth? How can progressive structural changes be implemented without hampering the rate of growth in general? What are the main external and internal risks, which may undermine positive trends of development? The author looks upon financial, monetary and foreign exchange aspects of the problem and comes up with some suggestions on how to make growth more competitive and sustainable.


2019 ◽  
Author(s):  
Bella Grigorenko ◽  
Igor Polyakov ◽  
Alexander Nemukhin

<p>We report a mechanism of adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP) conversion by the mammalian type V adenylyl cyclase revealed in molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) simulations. We characterize a set of computationally derived enzyme-substrate (ES) structures showing an important role of coordination shells of magnesium ions in the solvent accessible active site. Several stable six-fold coordination shells of Mg<sub>A</sub><sup>2+ </sup>are observed in MD simulations of ES complexes. In the lowest energy ES conformation, the coordination shell of Mg<sub>A</sub><sup>2+ </sup>does not include the O<sub>δ1</sub> atom of the conserved Asp440 residue. Starting from this conformation, a one-step reaction mechanism is characterized which includes proton transfer from the ribose O<sup>3'</sup>H<sup>3' </sup>group in ATP to Asp440 via a shuttling water molecule and P<sup>A</sup>-O<sup>3A</sup> bond cleavage and O<sup>3'</sup>-P<sup>A</sup> bond formation. The energy profile of this route is consistent with the observed reaction kinetics. In a higher energy ES conformation, Mg<sub>A</sub><sup>2+</sup> is bound to the O<sub>δ1</sub>(Asp440) atom as suggested in the relevant crystal structure of the protein with a substrate analog. The computed energy profile initiated by this ES is characterized by higher energy expenses to complete the reaction. Consistently with experimental data, we show that the Asp440Ala mutant of the enzyme should exhibit a reduced but retained activity. All considered reaction pathways include proton wires from the O<sup>3'</sup>H<sup>3' </sup>group via shuttling water molecules. </p>


2019 ◽  
Author(s):  
Whitney R. Ringwald ◽  
Aidan G.C. Wright

Empathy theoretically serves an affiliative interpersonal function by satisfying motives for intimacy and union with others. Accordingly, empathy is expected to vary depending on the situation. Inconsistent empirical support for empathy’s affiliative role may be due to methodology focused on individual differences in empathy or differences between controlled experimental conditions, which fail to capture its dynamic and interpersonal nature. To address these shortcomings, we used ecological momentary assessment to establish typical patterns of empathy across everyday interactions. Associations among empathy, affect, and interpersonal behavior of self and interaction partner were examined in a student sample (N=330), then replicated in a pre-registered community sample (N=279). Multi-level structural equation modeling was used to distinguish individual differences in empathy from interaction-level effects. Results show people are more empathetic during positively-valanced interactions with others perceived as warm and when expressing warmth. By confirming the typically affiliative role of empathy, existing research to the contrary can be best understood as exceptions to the norm.


2011 ◽  
Vol 162 (7) ◽  
pp. 209-215
Author(s):  
Jean-François Métraux

In the years since 2000, the authorities in charge of forests in canton Vaud have made some substantial changes as a reaction to the political decisions arising from the Swiss Forest Programme and the projected revision of the Federal forestry Law, as well as to the deterioration of the economic situation in forestry enterprises. This article gives a survey of the directions taken. Thus the canton recognises the primordial role of wood production as a driving force behind the creation of a multifunctional forest. The Service for Forests, Wildlife and Nature has invested a great deal in planning, and has redefined the management plan to be an instrument intended for forest owners and forest managers. The canton has innovated by introducing forestry groups and a scheme of equalisation of forestry costs between communes. Hence the conception of forestry management in canton Vaud is resolutely that of a multifunctional natural heritage.


2017 ◽  
pp. 126-169
Author(s):  
S.E. Tariverdieva

The article deals with the development of the coregency system of Augustus and Agrippa from 29 to 18 BC: from formal and actual disparity of the coregents to their formal equality with the dominance of the princeps auctoritas. Particular attention is paid to the earlier stages of this development and to the crisis of 23 BC. The coregency system created by Augustus is often regarded by modern historians as means of ensuring uninterrupted succession of power. Agrippa as his coregent often is thought to have assumed the role of the regent who temporally replaces the princeps, just as it was in formal monarchies, or that of the tutor of the future rulers. However, the Roman system of state administration did not allow such type of regency. The princeps coregent, who was his equal in formal credentials but his inferior in terms of auctoritas, in case of the princeps death had to become the next princeps as his immediate successor. It is unlikely that later he was expected to voluntarily give up his power in favour of younger heir and to vanish from the political life altogether. The inheritance system under Augustus was like a ladder with the princeps at the top, the coregent who was also the immediate successor one step below, heirs of the next degree further down. In case of death of one of them, successors shifted one step up. The coregency had one more function: geographically it allowed Augustus and Agrippa to rule jointly the empire while staying in different parts of it.В статье исследуется развитие системы соправления Августа и Агриппы с 29 по 12 гг. до н. э.: от формального и фактического неравенства соправителей до их формального равенства при преобладании auctoritas принцепса, причём особое внимание уделяется раннему этапу этого развития и кризису 23 г. до н. э. Институт соправления, созданный Августом, часто рассматривается, как средство обеспечения бесперебойного перехода власти, причем Агриппе, как соправителю, НЕРЕДКО отводится роль регента, временно замещающего принцепса или воспитателя будущих правителей. Однако римская система государственного управления не предполагала регентства. Соправитель принцепса, равный ему по формальным полномочиям, но уступавший по auctoritas, в случае его смерти должен был СТАТЬ следующим принцепсом, ближайшим его наследником. Вряд ли предполагалось, что в будущем он должен добровольно уступить власть более молодому наследнику и исчезнуть из политической жизни. Система наследования при Августе представляла собой нечто вроде лестницы, на вершине которой стоял принцепс, на следующей ступени соправитель, он же избранный преемник, ниже наследники следующей очереди в случае смерти когото из них происходило продвижение наследников по ступеням вверх. Кроме того, соправление имело и иное значение позволяло Августу и Агриппе совместно управлять империей, находясь в разных ее частях.


Author(s):  
Andrea Harris

The Conclusion briefly examines the current state of the New York City Ballet under the auspices of industrial billionaire David H. Koch at Lincoln Center. In so doing, it to introduces a series of questions, warranting still more exploration, about the rapid and profound evolution of the structure, funding, and role of the arts in America through the course of the twentieth century. It revisits the historiographical problem that drives Making Ballet American: the narrative that George Balanchine was the sole creative genius who finally created an “American” ballet. In contrast to that hagiography, the Conclusion reiterates the book’s major contribution: illuminating the historical construction of our received idea of American neoclassical ballet within a specific set of social, political, and cultural circumstances. The Conclusion stresses that the history of American neoclassicism must be seen as a complex narrative involving several authors and discourses and crossing national and disciplinary borders: a history in which Balanchine was not the driving force, but rather the outcome.


2021 ◽  
Vol 22 (9) ◽  
pp. 4484
Author(s):  
Ewa Filip ◽  
Lidia Skuza

Horizontal gene transfer (HGT)- is defined as the acquisition of genetic material from another organism. However, recent findings indicate a possible role of HGT in the acquisition of traits with adaptive significance, suggesting that HGT is an important driving force in the evolution of eukaryotes as well as prokaryotes. It has been noted that, in eukaryotes, HGT is more prevalent than originally thought. Mitochondria and chloroplasts lost a large number of genes after their respective endosymbiotic events occurred. Even after this major content loss, organelle genomes still continue to lose their own genes. Many of these are subsequently acquired by intracellular gene transfer from the original plastid. The aim of our review was to elucidate the role of chloroplasts in the transfer of genes. This review also explores gene transfer involving mitochondrial and nuclear genomes, though recent studies indicate that chloroplast genomes are far more active in HGT as compared to these other two DNA-containing cellular compartments.


2021 ◽  
Vol 127 (3) ◽  
Author(s):  
Umit Demirbas ◽  
Martin Kellert ◽  
Jelto Thesinga ◽  
Yi Hua ◽  
Simon Reuter ◽  
...  

AbstractWe present detailed experimental results with cryogenic Yb:YLF gain media in rod-geometry. We have comparatively investigated continuous-wave (cw) lasing and regenerative amplification performance under different experimental conditions. In the cw lasing experiments effect of crystal doping, cw laser cavity geometry and pump wavelength on lasing performance were explored. Regenerative amplification behavior was analyzed and the role of depolarization losses on performance was investigated. A recently developed temperature estimation method was also employed for the first time in estimating average crystal temperature under lasing conditions. It is shown that the thermal lens induced by transverse temperature gradients is the main limiting factor and strategies for future improvements are discussed. To the best of our knowledge, the achieved results in this study (375 W in cw, and 90 W in regenerative amplification) are the highest average powers ever obtained from this system via employing the broadband E//a axis.


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