Influence of bovine serum albumine on the proton conductance of potato mitochondria membranes

Ducet, Gaston

doi:10.1007/bf00389511

Cited by 10 publications

(11 citation statements)

References 2 publications

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“…In the presence of BSA, crude and purified mitochondria exhibited the same ADP:O value. Similar results have been reported on mitochondria purified on a sucrose gradient (Ducet 1979).…”

Section: Oitidalive Properties Of Potato Milachondriasupporting

confidence: 90%

“…The effect of BSA in crude preparations of mitochondria has been ascribed to a binding of free fatty acids Wojtczak 1960, Dalgarno andBirt 1963), Recently, tising sucrose purified mitochondria, the beneficial effect of BSA on both respiratory control and ADP:O ratios linked to substrate oxidation has also been ascribed to a possible direct interaction with the inner mitochondrial membrane. BSA would act in decreasing proton conductance (Ducet 1979). Recent reports by Ducet (1979Ducet ( , 1982 and preliminary studies by Moreau et al (1982) have also suggested that, in mitochondria oxidizing succinate, the rate of oxidation in state 4 is related to the proton conductance of the inner membrane.…”

Section: Introductionmentioning

confidence: 91%

“…BSA would act in decreasing proton conductance (Ducet 1979). Recent reports by Ducet (1979Ducet ( , 1982 and preliminary studies by Moreau et al (1982) have also suggested that, in mitochondria oxidizing succinate, the rate of oxidation in state 4 is related to the proton conductance of the inner membrane. Consequently, all effectors modifying proton conductance should modulate the rate of oxidation in state 4 and thus the respiratory control.…”

Section: Introductionmentioning

confidence: 91%

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Effect of bovine serum albumin on membrane potential in plant mitochondria

Diolez

Moreau

1983

Physiologia Plantarum

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The membrane potential in highly coupled potato (Solanum tuberosum L.) mitochondria, as measured by changes in safranine absorbance, was significantly increased by addition of bovine serum albumin. Purification of potato mitochondria on Percoll, in removing 50% of free unsaturated fatty acids, decreased the BSA‐de‐pendent membrane potential. The effect of added linoleic acid and of the natural accumulation of fatty acids during aging was studied. The response of membrane potential to addition of bovine serum albumin appeared to be directly correlated to the amount of free unsaturated fatty acids. Aging in vitro, in releasing free fatty acids, decreased respiratory control and ADP:O ratios and collapsed the membrane potential. During 2–3 h of incubation, addition of BSA completely restored membrane potential and oxidative phosphorylation. It is concluded that both in fresh and in aged potato mitochondria the effect of bovine serum albumin on oxidative phosphorylation can be ascribed to an effect on membrane permeability to ions. BSA, in binding free unsaturated fatty acids, restored maximal membrane potential. The bovine serum albumin‐dependent membrane potential appears to be a sensitive criterion of the functional integrity of the inner mitochondrial membrane.

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“…In the presence of BSA, crude and purified mitochondria exhibited the same ADP:O value. Similar results have been reported on mitochondria purified on a sucrose gradient (Ducet 1979).…”

Section: Oitidalive Properties Of Potato Milachondriasupporting

confidence: 90%

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 91%

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Effect of bovine serum albumin on membrane potential in plant mitochondria

Diolez

Moreau

1983

Physiologia Plantarum

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“…Experimental conditions were identical to those described in the legend to Fig. 3 used to desorb amphiphilic molecules from membranes (22) and to trap fatty acids freed from triglycerides by the action of lipase in lipid moiiblayer studies (23). Fig.…”

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confidence: 99%

In vivo properties of colicin A: channel activity is voltage dependent but translocation may be voltage independent.

Bourdineaud¹,

Boulanger²,

Lazdunski³

et al. 1990

Proc. Natl. Acad. Sci. U.S.A.

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The kinetics of K+ efflux caused by colicin A in Escherichia coli-sensitive cells have been investigated by using a KV-selective electrode. The order of magnitude of the rate of K+ efflux per colicin molecule was comparable to that ofion channels. The dependence of K+ efflux upon multiplicity, pH, temperature, and membrane potential (AI) was determined. The translocation ofcolicin A from the outer membrane receptor to the inner membrane and insertion into the inner membrane required a fluid membrane, but once inserted, the channel properties showed little dependence upon the state of the lipids. At a given multiplicity, the lag time before the onset of K+ efflux was found to reflect the time required for translocation and/or insertion of colicin into the cytoplasmic membrane. Opening of the channel only occurred above a threshold value of AI of 85 ± 10 and 110 ± 5 mV at pH 6.8 and 7.8, respectively. Conditions were designed for closing and reopening of the channel in vivo. These conditions allowed us to test separately the At requirements for translocation and channel opening: translocation and/or insertion did not appear to require At. The channel formed in vivo featured properties similar to that ofthe channel in lipid planar bilayers.

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“…Swelling was determined by light transmission at 520 nm in a standard medium of 100 mm KC1, 4 mi MgSO4, 25 ,ug/ml Ducet (10) has shown that the proton conductance of potato mitochondria is greatly reduced in the presence of BSA. In all the experiments reported here, BSA was included in the isolation and reaction media.…”

Section: Methodsmentioning

confidence: 99%

Mechanisms of Passive Potassium Influx in Corn Mitochondria

Fluegel¹,

Hanson²

1981

Plant Physiol.

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Corn mitochondria in 100 milHimolar KCI show accelerated passive swelling upon addition of uncoupler. This unusual response has been compared with swelling produced by valinomycin, tripropyltin, and nigericin. It is concluded that the driving force for swelling lies with the chloride gradient and a high PCI:PK ratio, the chloride influx creating a negative membrane potential. The action of uncoupler is to facilitate K+ influx via the endogenous H+/K+ antiporter. The antiporter is active over the pH range 6 to 8, is not sensitive to Mg2+ concentration, and is not inactivated by aging. It is not clear why corn mitochondria show this exceptional activity of the H+/K+ antiporter in K+ influx. It is speculated that during isolation the antiporter may be exposed or activated, and that it contributes to cyclic K+ transport and high State 4 respiration rates.ionophore TPT (26), should greatly accelerate the rate of salt entry and swelling. However, recent reports (17,20,24) indicate little if any KCI influx by this mechanism in plant mitochondria unless nigericin, an antibiotic carrying out neutral H+/K+ exchange, is introduced. The endogenous H+/K+ exchanger is believed to operate only in salt extrusion (20).An exception to this generalization may be found in corn mitochondria. Early experiments on passive swelling in KCI showed uncouplers to accelerate swelling (12,27). Analyses for KCI showed that swelling has an osmotic origin (22). Thus, it is possible that in corn mitochondria at least part of the KCI influx might be mediated through the H+/K+ antiport allowing K+ entry.We have utilized standard swelling techniques to examine this question. We conclude that in corn mitochondria the H+/K+ antiport is present and can act efficiently in KCI uptake. It is stable under varied conditions of pH, Mg + and aging. However, we suggest that it normally acts in K+ extrusion, stabilizing mitochondrial salt loads, and in this capacity may contribute significantly to State 4 respiration rates.On the basis of passive swelling in isotonic salt solutions it appears that mitochondria from several plant sources are permeable to chloride and nitrate (9,13,15,17,20,24,28,29) MATERIALS AND METHODSMitochondria were isolated by the "cushion" technique from 3 day etiolated corn shoots (9). The isolation medium contained 0.4 M sucrose, 50 mm Tes, 1 mg/ml BSA, 5 mm ethylene glycol-bis(flaminoethyl ether-N,N'-tetracetic acid, adjusted pH 7.6 with KOH. Oxidative phosphorylation was determined as described (9).Swelling was determined by light transmission at 520 nm in a standard medium of 100 mm KC1, 4 mi MgSO4, 25 ,ug/ml C for a few weeks do.In this report on KCI swelling in corn mitochondria we consider that the mitochondria meet normal standards for membrane integrity, and that the spontaneous, passive swelling in KC1 reflects the operation of normal avenues for ion transport.K+ and Cl-Content. Figure IA, and demonstrates that K+ permeation is the limiting factor in spontaneous swelling. Raising the pH increases both spontaneous and...

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Influence of bovine serum albumine on the proton conductance of potato mitochondria membranes

Cited by 10 publications

References 2 publications

Effect of bovine serum albumin on membrane potential in plant mitochondria

Effect of bovine serum albumin on membrane potential in plant mitochondria

In vivo properties of colicin A: channel activity is voltage dependent but translocation may be voltage independent.

Mechanisms of Passive Potassium Influx in Corn Mitochondria

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