scholarly journals The nature of controlled respiration and its relationship to protonmotive force and proton conductance in blowfly flight-muscle mitochondria

1977 ◽  
Vol 164 (2) ◽  
pp. 305-322 ◽  
Author(s):  
Roger N. Johnson ◽  
Richard G. Hansford
Keyword(s):  
Cytochrome C ◽  
Energy State ◽  
High Energy ◽  
The State ◽  
Protonmotive Force ◽  
Proton Conductance ◽  
Energy Status ◽  
Inner Membrane ◽  
Phosphorylation Potential ◽  
The Difference

1. To determine whether controlled (State 4) pyruvate oxidation can support a high energy state, measurements of the redox span NAD–cytochrome c, phosphorylation potential and protonmotive force (the gradient in electrochemical activity of protons across the mitochondrial inner membrane) were made as indices of energy status. For comparison, these three measurements were also made with glycerol 3-phosphate, an alternative substrate. The two substrates gave essentially identical values for the redox span NAD–cytochrome c in State 4, and the phosphorylation potential was of sufficient magnitude to be considered in equilibrium with the redox span over the first two phosphorylation sites. The magnitude of the protonmotive force in State 4 was much less and the implications of this finding are discussed. 2. Measurements made during the controlled (State 4) to active (State 3) transition indicated that with glycerol 3-phosphate as substrate, both the redox span NAD–cytochrome c and the protonmotive force were diminished; the State 4 → State 3 transition with pyruvate as substrate was accompanied by an increase in the redox span but a decrease in protonmotive force. The contrary behaviour of these two energetic parameters in the presence of pyruvate was ascribed to a transient excess in the flux of protons through the adenosine triphosphatase relative to the protonpumping respiratory chain, in spite of the increased dehydrogenase activity. 3. The lower protonmotive force seen in State 3 relative to State 4 with pyruvate as substrate was due to a diminution of both the electrical (ΔΨ) and the chemical (ΔpH) components; with glycerol 3-phosphate, the magnitude of the decrease in protonmotive force during the State 4 → State 3 transition was similar to that seen with pyruvate, but was due to a large decrease in the electrical component (ΔΨ) and a small rise in the chemical component (ΔpH). The reason for the difference seen in the behaviour of the components of the protonmotive force was investigated but not established. 4. In the presence of oligomycin and ADP, oxidation of pyruvate, but not of glycerol 3-phosphate, supported a greater protonmotive force than in State 4, in keeping with the dehydrogenase activation and increased redox span NAD–cytochrome c found under these conditions. 5. Experiments involving the use of uncoupling agent to stimulate respiration are compared with those in which limiting concentrations of ADP were used. Estimates of the proton conductance of the inner membrane indicate a similar non-linear dependence on uncoupler concentration with the two substrates. 6. A model is proposed as an explanation of the high rates of controlled glycerol 3-phosphate oxidation. The model relies on a high permeability of the inner membrane to protons and other ions being induced by glycerol 3-phosphate oxidation in State 4.

Pyruvate-fortified cardioplegia suppresses oxidative stress and enhances phosphorylation potential of arrested myocardium

2005 ◽  
Vol 289 (3) ◽  
pp. H1123-H1130 ◽  
Author(s):  
E. Marty Knott ◽  
Myoung-Gwi Ryou ◽  
Jie Sun ◽  
Abraham Heymann ◽  
Arti B. Sharma ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Redox State ◽  
Energy State ◽  
High Energy ◽  
High Energy Phosphates ◽  
Cardioplegic Arrest ◽  
Phosphorylation Potential ◽  
Lactate And Pyruvate ◽  
Postischemic Myocardium

Cardioplegic arrest for bypass surgery imposes global ischemia on the myocardium, which generates oxyradicals and depletes myocardial high-energy phosphates. The glycolytic metabolite pyruvate, but not its reduced congener lactate, increases phosphorylation potential and detoxifies oxyradicals in ischemic and postischemic myocardium. This study tested the hypothesis that pyruvate mitigates oxidative stress and preserves the energy state in cardioplegically arrested myocardium. In situ swine hearts were arrested for 60 min with a 4:1 mixture of blood and crystalloid cardioplegia solution containing 188 mM glucose alone (control) or with additional 23.8 mM lactate or 23.8 mM pyruvate and then reperfused for 3 min with cardioplegia-free blood. Glutathione (GSH), glutathione disulfide (GSSG), and energy metabolites [phosphocreatine (PCr), creatine (Cr), Pi] were measured in myocardium, which was snap frozen at 45 min arrest and 3 min reperfusion to determine antioxidant GSH redox state (GSH/GSSG) and PCr phosphorylation potential {[PCr]/([Cr][Pi])}. Coronary sinus 8-isoprostane indexed oxidative stress. Pyruvate cardioplegia lowered 8-isoprostane release ∼40% during arrest versus control and lactate cardioplegia. Lactate and pyruvate cardioplegia dampened ( P < 0.05 vs. control) the surge of 8-isoprostane release following reperfusion. Pyruvate doubled GSH/GSSG versus lactate cardioplegia during arrest, but GSH/GSSG fell in all three groups after reperfusion. Myocardial [PCr]/([Cr][Pi]) was maintained in all three groups during arrest. Pyruvate cardioplegia doubled [PCr]/([Cr][Pi]) versus control and lactate cardioplegia after reperfusion. Pyruvate cardioplegia mitigates oxidative stress during cardioplegic arrest and enhances myocardial energy state on reperfusion.

scholarly journals Mitochondrial glycerol phosphate oxidation is modulated by adenylates through allosteric regulation of cytochrome c oxidase activity in mosquito flight muscle

2019 ◽  
Author(s):  
Alessandro Gaviraghi ◽  
Juliana B.R. Correa Soares ◽  
Julio A. Mignaco ◽  
Carlos Frederico L. Fontes ◽  
Marcus F. Oliveira
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Energy Demand ◽  
Flight Muscle ◽  
Allosteric Regulation ◽  
High Energy ◽  
Protonmotive Force ◽  
Independent Manner ◽  
Oxidoreductase Activity ◽  
Regulatory Effects

AbstractThe huge energy demand posed by insect flight activity is met by an efficient oxidative phosphorylation process that takes place within flight muscle mitochondria. In the major arbovirus vector Aedes aegypti, mitochondrial oxidation of pyruvate, proline and glycerol 3 phosphate (G3P) represent the major energy sources of ATP to sustain flight muscle energy demand. Although adenylates exert critical regulatory effects on several mitochondrial enzyme activities, the potential consequences of altered adenylate levels to G3P oxidation remains to be determined. Here, we report that mitochondrial G3P oxidation is controlled by adenylates through allosteric regulation of cytochrome c oxidase (COX) activity in A. aegypti flight muscle. We observed that ADP significantly activated respiratory rates linked to G3P oxidation, in a protonmotive force-independent manner. Kinetic analyses revealed that ADP activates respiration through a slightly cooperative mechanism. Despite adenylates caused no effects on G3P-cytochrome c oxidoreductase activity, COX activity was allosterically activated by ADP. Conversely, ATP exerted powerful inhibitory effects on respiratory rates linked to G3P oxidation and on COX activity. We also observed that high energy phosphate recycling mechanisms did not contribute to the regulatory effects of adenylates on COX activity or G3P oxidation. We conclude that mitochondrial G3P oxidation by A. aegypti flight muscle is regulated by adenylates essentially through the allosteric modulation of COX activity, underscoring the bioenergetic relevance of this novel mechanism and the potential consequences for mosquito dispersal.

The Non-Ohmic Proton Leak—25 Years On

1997 ◽  
Vol 17 (3) ◽  
pp. 251-257 ◽  
Author(s):  
David G. Nicholls
Keyword(s):  
Ion Transport ◽  
Respiratory Chain ◽  
Atp Synthesis ◽  
Proton Leak ◽  
Protonmotive Force ◽  
Proton Conductance ◽  
Inner Membrane ◽  
Ohm’S Law ◽  
Mitochondrial Inner Membrane ◽  
Proton Current

The proton conductance of the mitochondrial inner membrane can be quantified by applying Ohm's law to the experimentally determined protonmotive force and the proton current flowing around the proton circuit in the absence of ATP synthesis or ion transport. This last parameter is derived from the rate of State 4 respiration multiplied by the H+/O stoichiometry for the substrate. When the activity of the dehydrogenase supplying electrons to the respiratory chain is progressively increased the proton conductance increases rapidly when the protonmotive force is greater than 220 mV. The consequences of this non-ohmic relationship are discussed.

Mitochondrial cytochrome c oxidase and control of energy metabolism: measurements in suspensions of isolated mitochondria

2014 ◽  
Vol 117 (12) ◽  
pp. 1424-1430 ◽  
Author(s):  
David F. Wilson ◽  
David K. Harrison ◽  
Andrei Vinogradov
Keyword(s):  
Oxygen Consumption ◽  
Energy Metabolism ◽  
Cytochrome C ◽  
Oxidative Phosphorylation ◽  
Respiratory Rate ◽  
Cytochrome C Oxidase ◽  
Energy State ◽  
Atp Synthesis ◽  
Oxygen Depletion ◽  
High Energy

Cytochrome c oxidase is the enzyme responsible for oxygen consumption by mitochondrial oxidative phosphorylation and coupling site 3 of oxidative phosphorylation. In this role it determines the cellular rate of ATP synthesis by oxidative phosphorylation and is the key to understanding how energy metabolism is regulated. Four electrons are required for the reduction of oxygen to water, and these are provided by the one-electron donor, cytochrome c. The rate of oxygen consumption (ATP synthesis) is dependent on the fraction of cytochrome c reduced (fred), oxygen pressure (pO2), energy state ([ATP]/[ADP][Pi]), and pH. In coupled mitochondria (high energy state) and pO2 >60 torr, the rate increases in an exponential-like fashion with increasing fred. When the dependence on fred is fitted to the equation rate = a(fred)b, a decreased from 100 to near 20, and b increased from 1.3 to 4 as the pH of the medium increased from 6.5 to 8.3. During oxygen depletion from the medium fred progressively increases and the rate of respiration decreases. The respiratory rate falls to ½ (P50) by about 1.5 torr, at which point fred is substantially increased. The metabolically relevant dependence on pO2 is obtained by correcting for the increase in fred, in which case the P50 is 12 torr. Adding an uncoupler of oxidative phosphorylation eliminates the dependence of the cytochrome c oxidase activity on pH and energy state. The respiratory rate becomes proportional to fred and the P50 decreases to less than 1 torr.

High-resolution EM study of submicrometer-grained Al-Mg solid solution alloys

1995 ◽  
Vol 53 ◽  
pp. 524-525
Author(s):  
Z. Horita ◽  
D. J. Smith ◽  
M. Furukawa ◽  
M. Nemoto ◽  
R. Z. Valiev ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
High Resolution ◽  
Grain Boundaries ◽  
Energy State ◽  
High Energy ◽  
Grain Structure ◽  
Boundary Structure ◽  
Solid Solution Alloy ◽  
Average Grain Size

It is possible to produce metallic materials with submicrometer-grained (SMG) structures by imposing an intense plastic strain under quasi-hydrostatic pressure. Studies using conventional transmission electron microscopy (CTEM) showed that many grain boundaries in the SMG structures appeared diffuse in nature with poorly defined transition zones between individual grains. The implication of the CTEM observations is that the grain boundaries of the SMG structures are in a high energy state, having non-equilibrium character. It is anticipated that high-resolution electron microscopy (HREM) will serve to reveal a precise nature of the grain boundary structure in SMG materials. A recent study on nanocrystalline Ni and Ni3Al showed lattice distortion and dilatations in the vicinity of the grain boundaries. In this study, HREM observations are undertaken to examine the atomic structure of grain boundaries in an SMG Al-based Al-Mg alloy.An Al-3%Mg solid solution alloy was subjected to torsion straining to produce an equiaxed grain structure with an average grain size of ~0.09 μm.

Analysis of the horizontal structure of a measurement and control geodetic network based on entropy

2013 ◽  
Vol 62 (1) ◽  
pp. 23-31 ◽  
Author(s):  
Maria Mrówczyńska
Keyword(s):  
Geodetic Network ◽  
The State ◽  
Observation System ◽  
Optimum Number ◽  
Optimum Structure ◽  
Horizontal Structure ◽  
The Difference ◽  
And Control ◽  
Measurement And Control ◽  
Horizontal Displacements

Abstract The paper attempts to determine an optimum structure of a directional measurement and control network intended for investigating horizontal displacements. For this purpose it uses the notion of entropy as a logarithmical measure of probability of the state of a particular observation system. An optimum number of observations results from the difference of the entropy of the vector of parameters ΔHX̂ (x)corresponding to one extra observation. An increment of entropy interpreted as an increment of the amount of information about the state of the system determines the adoption or rejection of another extra observation to be carried out.

TO THE PROBLEMS OF COMBATING CORRUPTION IN MODERN RUSSIA AND INTERNATIONAL COOPERATION IN THE FIELD OF ANTI-CORRUPTION

2020 ◽  
Author(s):  
Angela Dranishnikova
Keyword(s):  
Large Scale ◽  
The State ◽  
Point Of View ◽  
Modern Life ◽  
Existing Problems ◽  
Moral Point ◽  
Material Goods ◽  
The Russian Federation ◽  
The Difference ◽  
The Government

In the article, the author reflects the existing problems of the fight against corruption in the Russian Federation. He focuses on the opacity of the work of state bodies, leading to an increase in bribery and corruption. The topic we have chosen is socially exciting in our days, since its significance is growing on a large scale at all levels of the investigated aspect of our modern life. Democratic institutions are being jeopardized, the difference in the position of social strata of society in society’s access to material goods is growing, and the state of society is suffering from the moral point of view, citizens are losing confidence in the government, and in the top officials of the state.

Konsep Distribusi Pendapatan Dalam Islam

2016 ◽  
Vol 1 (1) ◽  
pp. 85-97
Author(s):  
Moh. Ah. Subhan ZA
Keyword(s):  
Property Rights ◽  
Social Life ◽  
Private Property ◽  
Wealth Distribution ◽  
The State ◽  
Private Property Rights ◽  
Job Opportunities ◽  
The Rich ◽  
The Difference ◽  
Distribution Of Income

The main problem of social life in the community is about how to make the allocation and distribution of income well. Inequality and poverty basically arise not because of the difference of anyone’s strength and weakness in getting livelihood, but because of inappropriate distribution mechanism. With the result that wealth treasure just turns on the rich wealthy, which is in turn, results in the rich get richer and the poor get poorer.Therefore, a discussion on distribution becomes main focus of theory of Islamic economics. Moreover, the discussion of the distribution is not only related to economic issues, but also social and political aspects. On the other side, the economic vision of Islam gives priority to the guarantee of the fulfillment of a better life. Islam emphasizes distributive justice and encloses, in its system, a program for the redistribution of wealth and prosperity, so that each individual is guaranteed with a respectable and friendly standard of living. Islam recognizes private property rights, but the private property rights must be properly distributed. The personal property is used for self and family livelihood, for investment of the working capital, so that it can provide job opportunities for others, for help of the others through zakat, infaq, and shodaqoh. In this way, the wealth not only rotates on the rich, bringing on gap in social life.The problem of wealth distribution is closely related to the welfare of society. Therefore, the state has a duty to regulate the distribution of income in order that the distribution can be fair and reaches appropriate target. The state could at least attempt it by optimizing the role of BAZ (Badan Amil Zakat) and LAZ (Lembaga Amil Zakat) which has all this time been slack. If BAZ and LAZ can be optimized, author believes that inequality and poverty over time will vanish. This is because the majority of Indonesia's population is Muslim.

Survey for Transition of Normal Reaction

2018 ◽  
Vol 5 (3) ◽  
Author(s):  
Hassan Akbari Rahimi
Keyword(s):  
Transition State ◽  
Reactive Intermediates ◽  
The State ◽  
Energy Profile ◽  
Normal Reaction ◽  
Unstable Molecules ◽  
The Difference ◽  
Bond Vibration ◽  
Unstable Molecule ◽  
Profile Diagram

Transition of reaction is a short-lived unstable molecule in a reaction which is formed in between the reaction when reactants change into products. Whereas, transition state is just the state before formation of new molecule (involves breaking of bonds of reactants and formation of new ones) Transition of reaction differs from a transition state in that the intermediate has a discrete lifetime (be it a few nanoseconds or many days), whereas a transition state lasts for just one bond vibration cycle. Intermediates may be unstable molecules (in which case they are called reactive intermediates) or highly stable molecules. The difference between them can be better described through the energy profile diagram.

scholarly journals Smoke recognition network based on dynamic characteristics

2020 ◽  
Vol 17 (3) ◽  
pp. 172988142092566
Author(s):  
Dahan Wang ◽  
Sheng Luo ◽  
Li Zhao ◽  
Xiaoming Pan ◽  
Muchou Wang ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
State Of The Art ◽  
The State ◽  
Detection Accuracy ◽  
Static Characteristics ◽  
Good Tool ◽  
Early Signal ◽  
Fuzzy Objects ◽  
The Difference ◽  
Smoke Recognition

Fire is a fierce disaster, and smoke is the early signal of fire. Since such features as chrominance, texture, and shape of smoke are very special, a lot of methods based on these features have been developed. But these static characteristics vary widely, so there are some exceptions leading to low detection accuracy. On the other side, the motion of smoke is much more discriminating than the aforementioned features, so a time-domain neural network is proposed to extract its dynamic characteristics. This smoke recognition network has these advantages:(1) extract the spatiotemporal with the 3D filters which work on dynamic and static characteristics synchronously; (2) high accuracy, 87.31% samples being classified rightly, which is the state of the art even in a chaotic environments, and the fuzzy objects for other methods, such as haze, fog, and climbing cars, are distinguished distinctly; (3) high sensitiveness, smoke being detected averagely at the 23rd frame, which is also the state of the art, which is meaningful to alarm early fire as soon as possible; and (4) it is not been based on any hypothesis, which guarantee the method compatible. Finally, a new metric, the difference between the first frame in which smoke is detected and the first frame in which smoke happens, is proposed to compare the algorithms sensitivity in videos. The experiments confirm that the dynamic characteristics are more discriminating than the aforementioned static characteristics, and smoke recognition network is a good tool to extract compound feature.

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