scholarly journals The rate of ATP synthesis by submitochondrial particles can be independent of the magnitude of the protonmotive force

1980 ◽  
Vol 188 (3) ◽  
pp. 945-948 ◽  
Author(s):  
M C Sorgato ◽  
D Branca ◽  
S J Ferguson
Keyword(s):  
Atp Synthesis ◽  
Substrate Oxidation ◽  
Protonmotive Force ◽  
Submitochondrial Particles

The problem of whether the rate of ATP synthesis is proportional to the magnitude of the protonmotive force has been studied in submitochondrial particles. It was found that the rate of ATP synthesis can decrease at constant protonmotive force and is more closely related to the rate of substrate oxidation.

scholarly journals The protonmotive force in bovine heart submitochondrial particles. Magnitude, sites of generation and comparison with the phosphorylation potential

1978 ◽  
Vol 174 (1) ◽  
pp. 237-256 ◽  
Author(s):  
M C Sorgato ◽  
S J Ferguson ◽  
D B Kell ◽  
P John
Keyword(s):  
Membrane Potential ◽  
Reaction Medium ◽  
Atp Synthesis ◽  
Ph Gradient ◽  
Protonmotive Force ◽  
Submitochondrial Particles ◽  
Electron Mediator ◽  
Phosphorylation Potential ◽  
Bovine Heart ◽  
Gradient Component

1. The magnitude of the protonmotive force in respiring bovine heart submitochondrial particles was estimated. The membrane-potential component was determined from the uptake of S14CN-ions, and the pH-gradient component from the uptake of [14C]methylamine. In each case a flow-dialysis technique was used to monitor uptake. 2. With NADH as substrate the membrane potential was approx. 145mV and the pH gradient was between 0 and 0.5 unit when the particles were suspended in a Pi/Tris reaction medium. The addition of the permeant NO3-ion decreased the membrane potential with a corresponding increase in the pH gradient. In a medium containing 200mM-sucrose, 50mM-KCl and Hepes as buffer, the total protonmotive force was 185mV, comprising a membrane potential of 90mV and a pH gradient of 1.6 units. Thus the protonmotive force was slightly larger in the high-osmolarity medium. 3. The phosphorylation potential (= deltaG0′ + RT ln[ATP]/[ADP][Pi]) was approx. 43.1 kJ/mol (10.3kcal/mol) in all the reaction media tested. Comparison of this value with the protonmotive force indicates that more than 2 and up to 3 protons must be moved across the membrane for each molecule of ATP synthesized by a chemiosmotic mechanism. 4. Succinate generated both a protonmotive force and a phosphorylation potential that were of similar magnitude to those observed with NADH as substrate. 5. Although oxidation of NADH supports a rate of ATP synthesis that is approximately twice that observed with succinate, respiration with either of these substrates generated a very similar protonmotive force. Thus there seemed to be no strict relation between the size of the protonmotive force and the phosphorylation rate. 6. In the presence of antimycin and/or 2-n-heptyl-4-hydroxyquinoline N-oxide, ascorbate oxidation with either NNN'N′-tetramethyl-p-phenylenediamine or 2,3,5,6-tetramethyl-p-phenylenediamine as electron mediator generated a membrane potential of approx. 90mV, but no pH gradient was detected, even in the presence of NO3-. These data are discussed with reference to the proposal that cytochrome oxidase contains a proton pump.

scholarly journals A comparison of the effects of NN′-dicyclohexylcarbodi-imide, oligomycin A and aurovertin on energy-linked reactions in mitochondria and submitochondrial particles

1968 ◽  
Vol 108 (3) ◽  
pp. 445-456 ◽  
Author(s):  
A. M. Roberton ◽  
Caroline T. Holloway ◽  
I G Knight ◽  
R B Beechey
Keyword(s):  
Potent Inhibitor ◽  
Atp Synthesis ◽  
Mitochondrial Fraction ◽  
Optimum Concentration ◽  
Submitochondrial Particles ◽  
Nicotinamide Nucleotide Transhydrogenase ◽  
Oligomycin A ◽  
Submitochondrial Particle ◽  
Site Of Action ◽  
Stimulation Of

1. The effects of dicyclohexylcarbodi-imide, oligomycin A and aurovertin on enzyme systems related to respiratory-chain phosphorylation were compared. Dicyclohexylcarbodi-imide and oligomycin A have very similar functional effects, giving 50% inhibition of ATP-utilizing and ATP-generating systems at concentrations below 0·8nmole/mg. of submitochondrial-particle protein. Aurovertin is a more potent inhibitor of ATP synthesis, giving 50% inhibition at 0·2nmole/mg. of protein. However, aurovertin is a less potent inhibitor of ATP-utilizing systems: the ATP-driven energy-linked nicotinamide nucleotide transhydrogenase is 50% inhibited at 3·0nmoles/mg. of protein and the ATP-driven reduction of NAD+ by succinate is 50% inhibited at 0·95nmole/mg. of protein. 2. With EDTA-particles (prepared by subjecting mitochondria to ultrasonic radiation at pH9 in the presence of 2mm-EDTA) the maximum stimulation of the ATP-driven partial reactions is effected by similar concentrations of oligomycin A and dicylcohexylcarbodi-imide, but the latter is less effective. The stimulatory effects of suboptimum concentrations of dicyclohexylcarbodi-imide and oligomycin A are additive. Aurovertin does not stimulate these reactions or interfere with the stimulation by the other inhibitors. 3. Dicyclohexylcarbodi-imide and oligomycin A stimulate the aerobic energy-linked nicotinamide nucleotide transhydrogenase of EDTA-particles, but the optimum concentration is higher than that required for the ATP-driven partial reactions. Aurovertin has no effect on this reaction. 4. The site of action of dicyclohexylcarbodi-imide is in CF0, the mitochondrial fraction that confers oligomycin sensitivity on F1 mitochondrial adenosine triphosphatase.

scholarly journals Effect of 3,5-di-iodo-L-thyronine on the mitochondrial energy-transduction apparatus

1998 ◽  
Vol 330 (1) ◽  
pp. 521-526 ◽  
Author(s):  
Assonta LOMBARDI ◽  
Antonia LANNI ◽  
Maria MORENO ◽  
D. Martin BRAND ◽  
Fernando GOGLIA
Keyword(s):  
Cytochrome C ◽  
Mitochondrial Respiration ◽  
Atp Synthesis ◽  
Substrate Oxidation ◽  
Energy Transduction ◽  
Energy Utilization ◽  
Proton Leak ◽  
Elasticity Analysis ◽  
Top Down ◽  
Respiratory State

We examined the effect of a single injection of 3,5-di-iodo-l-thyronine (3,5-T2) (150 μg/100 g body weight) on the rat liver mitochondrial energy-transduction apparatus. We applied ‘top-down’ elasticity analysis, which allows identification of the site of action of an effector within a metabolic pathway. This kinetic approach considers oxidative phosphorylation as two blocks of reactions: those generating the mitochondrial inner-membrane potential (Δψ; ‘substrate oxidation’) and those ‘consuming’ it (‘proton leak’ and ‘phosphorylating system’). The results show that 1 h after the injection of 3,5-T2, state 4 (respiratory state in which there is no ATP synthesis and the exogenous ADP added has been exhausted) and state 3 (respiratory state in which ATP synthesis is at maximal rate) of mitochondrial respiration were significantly increased (by approx. 30%). ‘Top-down’ elasticity analysis revealed that these increases were due to the stimulation of reactions involved in substrate oxidation; neither ‘proton leak’ nor the ‘phosphorylating system’ was influenced by 3,5-T2. Using the same approach we divided the respiratory chain into two blocks of reactions: cytochrome c reducers and cytochrome c oxidizers. We found that both cytochrome c reducers and cytochrome c oxidizers are targets for 3,5-T2. The rapidity with which 3,5-T2 acts in stimulating the mitochondrial respiration rate suggests to us that di-iodo-L-thyronine may play an important role in the physiological conditions in which rapid energy utilization is required, such as cold exposure or overfeeding.

Inhibition of Succinic Dehydrogenase and F0F1-ATP Synthase by 4,4'-Diisothiocyanatostilbene-2,2'-disulfonic Acid (DIDS)

1997 ◽  
Vol 52 (11-12) ◽  
pp. 799-806 ◽  
Author(s):  
Celene F. Bernardes ◽  
Jose R. Meyer-Fernandes ◽  
Orlando B. Martins ◽  
Anibal E. Vercesi
Keyword(s):  
Succinic Dehydrogenase ◽  
Atp Synthesis ◽  
Liver Mitochondria ◽  
Disulfonic Acid ◽  
Rat Liver Mitochondria ◽  
Dependent Manner ◽  
Submitochondrial Particles ◽  
Succinate Oxidation ◽  
Hydrolytic Activities ◽  
Dose Dependent

Abstract This study shows that incubation of rat liver mitochondria in the presence of the thiol/ amino reagent 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DID S) is followed by inhibition of both succinate supported respiration and oxidative phosphorylation. Half-maximal inhibition of succinic dehydrogenase activity and succinate oxidation by mitochondria was attained at 55.3 and 60.8 μm DIDS, respectively. DIDS did inhibit the net ATP synthesis and ATP ⇔ [32P]Pi exchange reaction catalyzed by submitochondrial particles in a dose-dependent manner (Ki= 31.7 μm and Ki = 32.7 μm), respectively. The hydrolytic activities of uncoupled heart submitochondrial particles and purified F 1 -ATPase were also inhibited 50% by 31.9 and 20.9 μm DIDS, respectively.

scholarly journals THe proton-per-electron stoicheiometry of ‘site 1’ of oxidative phosphorylation at high protonmotive force is close to 1.5

1982 ◽  
Vol 204 (2) ◽  
pp. 515-523 ◽  
Author(s):  
P C de Jonge ◽  
H V Westerhoff
Keyword(s):  
Redox Potential ◽  
Redox State ◽  
Dynamic Equilibrium ◽  
Experimental Situation ◽  
Potential Difference ◽  
Protonmotive Force ◽  
Submitochondrial Particles ◽  
Output Force ◽  
Group Translocation ◽  
Static Head

The maximum redox potential difference between the NAD+/NADH couple and the succinate/fumarate couple generated during ATP-energized reduction of NAD+ by succinate in submitochondrial particles was measured, together with the electrochemical potential difference for protons (delta mu approximately H+). The presence of cyanide, the time-independence of the redox potential difference and the irrelevance of the initial redox state of the NAD+/NADH couple ensured that the experimental situation corresponded to a ‘static-head condition’ with delta mu approximately H+ as the input force and the redox potential difference as the output force, the flow of electrons having reached dynamic equilibrium. Consequently, the observed value of 1.6 for the ratio delta Ge/delta mu approximately H+ is interpreted as indicating that the leads to H+/e- stoicheiometry at ‘site 1’ is 1.5 and that therefore the mechanism of the proton pump at ‘site 1’ is not of the group-translocation type (no direct leads to e - leads to H+ coupling).

scholarly journals Oxygen-pulse curves in rat liver mitochondrial suspensions. Some observations and deductions

1979 ◽  
Vol 180 (1) ◽  
pp. 161-174 ◽  
Author(s):  
G P Archbold ◽  
C L Farrington ◽  
S A Lappin ◽  
A M McKay ◽  
F H Malpress
Keyword(s):  
Rat Liver ◽  
Atp Synthesis ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Protonmotive Force ◽  
Mitochondrial Inner Membrane ◽  
Fixed Charges ◽  
Charge Concentration ◽  
C 50 ◽  
Proton Movement

1. The inference, implicit in the chemiosmotic hypothesis, that protons move into the bulk phase during ATP synthesis was investigated. 2. Incubation of rat liver mitochondria in the presence of the cation exchanger CM-Sephadex C-50 caused alkalinization in the medium, though total ATP synthesis remained unchanged. The addition of N-ethylmaleimide prevented the alkalinization, but there was still no indication of protons passing into the medium. The expected proton movement [Mitchell & Moyle (1967) Biochem. J. 105, 1147–1162] was readily detected when as an equivalent acid pulse. 3. Analysis of delta H+ decay curves after O2 pulses (3 micrograms-atoms of O/g of protein) indicated the presence of fast and slow components of decay, with first-order rate constants (k) of 0.24s-1 and 0.032s-1. The fast decay was finite and was eliminated in the presence of N-ethylmaleimide. 4. These observations are interpreted as evidence for the development of unmasking of fixed charges on the outer surface of the mitochondrial inner membrane during energization and for the existence of proton-retentive electrical fields (rho-zones) on this surface. The charge concentration is calculated as about 1 charge/10nm2. 5. A cycle of changes in a single fixed-charge molecule is proposed which mediates both Ca2+ uptake and the first step in the utilization of the rho-zone protonmotive force, delta p rho.

scholarly journals Control of oxidative phosphorylation during insect metamorphosis

2004 ◽  
Vol 287 (2) ◽  
pp. R314-R321 ◽  
Author(s):  
M. E. Chamberlin
Keyword(s):  
Membrane Potential ◽  
Oxidative Phosphorylation ◽  
Adenine Nucleotide ◽  
Substrate Oxidation ◽  
Proton Leak ◽  
Protonmotive Force ◽  
Control Analysis ◽  
Membrane Area ◽  
Early Stages ◽  
Oxidation System

The midgut of the tobacco hornworm ( Manduca sexta) is a highly aerobic tissue that is destroyed and replaced by a pupal epithelium at metamorphosis. To determine how oxidative phosphorylation is altered during the programmed death of the larval cells, top-down control analysis was performed on mitochondria isolated from the midguts of larvae before and after the commitment to pupation. Oxygen consumption and protonmotive force (measured as membrane potential in the presence of nigericin) were monitored to determine the kinetic responses of the substrate oxidation system, proton leak, and phosphorylation system to changes in the membrane potential. Mitochondria from precommitment larvae have higher respiration rates than those from postcommitment larvae. State 4 respiration is controlled by the proton leak and the substrate oxidation system. In state 3, the substrate oxidation system exerted 90% of the control over respiration, and this high level of control did not change with development. Elasticity analysis, however, revealed that, after commitment, the activity of the substrate oxidation system falls. This decline may be due, in part, to a loss of cytochrome c from the mitochondria. There are no differences in the kinetics of the phosphorylation system, indicating that neither the F1F0 ATP synthase nor the adenine nucleotide translocase is affected in the early stages of metamorphosis. An increase in proton conductance was observed in mitochondria isolated from postcommitment larvae, indicating that membrane area, lipid composition, or proton-conducting proteins may be altered during the early stages of the programmed cell death of the larval epithelium.

scholarly journals Neuronal AMPK coordinates mitochondrial energy sensing and hypoxia resistance

2020 ◽  
Author(s):  
Brandon J. Berry ◽  
Aksana Baldzizhar ◽  
Andrew P. Wojtovich
Keyword(s):  
Protein Kinase ◽  
Mitochondrial Function ◽  
Stress Resistance ◽  
Atp Synthesis ◽  
Protonmotive Force ◽  
Electrochemical Gradient ◽  
Energy Sensing ◽  
Amp Activated Protein Kinase ◽  
Spatiotemporal Control

ABSTRACTOrganisms adapt to their environment through coordinated changes in mitochondrial function and metabolism. The mitochondrial protonmotive force (PMF) is an electrochemical gradient that powers ATP synthesis and adjusts metabolism to energetic demands via cellular signaling. It is unknown how or where transient PMF changes are sensed and signaled due to lack of precise spatiotemporal control in vivo. We addressed this by expressing a light-activated proton pump in mitochondria to spatiotemporally “turn off” mitochondrial function through PMF dissipation in tissues with light. We applied our construct – mitochondria-OFF (mtOFF) – to understand how metabolic status impacts hypoxia resistance, a response that relies on mitochondrial function. mtOFF activation induced starvation-like behavior mediated by AMP-activated protein kinase (AMPK). We found prophylactic mtOFF activation increased survival following hypoxia, and that protection relied on neuronal AMPK. Our study links spatiotemporal control of mitochondrial PMF to cellular metabolic changes that mediate behavior and stress resistance.

Sign in / Sign up

Export Citation Format

Share Document