Free fatty acids dissipate proton electrochemical gradients in pea stem microsomes and submitochondrial particles

Macrı̀, Francesco; Vianello, Angelo; Braidot, Enrico; Zancani, Marco

doi:10.1016/s0005-2728(05)80244-0

Cited by 23 publications

(9 citation statements)

References 32 publications

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“…1). It is well known that FFAs facilitate the proton diffusion and cation/proton exchange in several liposomal preparations, as reported previously (Cooper et al, 1990;Macri et al, 1991). In addition, the characteristic lipid composition of myelin, with an elevated content in cholesterol and sphingolipids (Fig.…”

Section: Discussionsupporting

confidence: 74%

Unusual Low Proton Permeability of Liposomes Prepared from the Endogenous Myelin Lipids

Díaz

Monreal

1994

Journal of Neurochemistry

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In contrast with most other lipid substrates, in this article we show that liposomes prepared from the total myelin lipids exhibited a negligible proton permeability. Neither the generation of valinomycin‐induced potassium diffusion potentials as high as ‐177 mV nor the imposition of large pH gradients (up to three units) was able to produce a substantial flux of protons through liposomal membranes, as determined by the distribution of [14C]‐methylamine, or the changes in the fluorescence of the probes 9‐aminoacridine, acridine orange, and pyranine. The presence of cations (Na+, K+, Ca2+) did not alter this behavior. Voltage clamping did not increase the trans‐membrane ApH‐driven proton permeability. However, II‐posome diameter was found to be critical because small unilamellar vesicles displayed a much higher proton permeability than large unilamellar or multilamellar vesicles. This abnormally low proton permeability is interpreted by virtue of the characteristic biochemical composition of myelin lipid matrix, with a high content of cholesterol and sphingolipids and a very low level of free fatty acids. These results could be important for elucidating the role of myelin in the regulation of pH in the brain. In addition, the myelin lipid extract could be useful for reconstituting proteins that participate in the transport of H+ through the membrane.

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Section: Discussionsupporting

confidence: 74%

Unusual Low Proton Permeability of Liposomes Prepared from the Endogenous Myelin Lipids

Díaz

Monreal

1994

Journal of Neurochemistry

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“…Pea ( Pisum sativum L., cv. Frimousse) mitochondria were isolated from 7‐day‐old etiolated seedlings, as previously described [22]. Briefly, 70 g of stems were cut and homogenized by a mortar with a pestle in 120 ml of a medium composed of 20 mM HEPES‐Tris (pH 7.6), 0.4 M sucrose, 5 mM EDTA, 25 mM potassium metabisulfite and 0.3% bovine serum albumin (BSA).…”

Section: Methodsmentioning

confidence: 99%

Hydrogen peroxide generation by higher plant mitochondria oxidizing complex I or complex II substrates

et al. 1999

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The generation of H 2 O 2 by isolated pea stem mitochondria, oxidizing either malate plus glutamate or succinate, was examined. The level of H 2 O 2 was almost one order of magnitude higher when mitochondria were energized by succinate. The succinate-dependent H 2 O 2 formation was abolished by malonate, but unaffected by rotenone. The lack of effect of the latter suggests that pea mitochondria were working with a proton motive force below the threshold value required for reverse electron transfer. The activation by pyruvate of the alternative oxidase was reflected in an inhibition of H 2 O 2 formation. This effect was stronger when pea mitochondria oxidized malate plus glutamate. Succinate-dependent H 2 O 2 formation was ca. four times lower in Arum sp. mitochondria (known to have a high alternative oxidase) than in pea mitochondria. An uncoupler (FCCP) completely prevented succinate-dependent H 2 O 2 generation, while it only partially (40^50%) inhibited that linked to malate plus glutamate. ADP plus inorganic phosphate (transition from state 4 to state 3) also inhibited the succinate-dependent H 2 O 2 formation. Conversely, that dependent on malate plus glutamate oxidation was unaffected by low and stimulated by high concentrations of ADP. These results show that the main bulk of H 2 O 2 is formed during substrate oxidation at the level of complex II and that this generation may be prevented by either dissipation of the electrochemical proton gradient (uncoupling and transition state 4-state 3), or preventing its formation (alternative oxidase). Conversely, H 2 O 2 production, dependent on oxidation of complex I substrate, is mainly lowered by the activation of the alternative oxidase.z 1999 Federation of European Biochemical Societies.

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“…In these circumstances, hence, pahnitate-induced uncoupling of oxidative phosphorylation may in part be explained by the involvement of ATP/ADP antiporter in FFA-induced uncoupling [5]. The lack of effect of CAtr on the pahnitate-dissipated dY and on the palmitatestimulated oxygen uptake by pea stem mitochondria [3,4], can now be explained by both the low content of ATP/ADP translocator present in these mitochondria and by the higher concentration of palmitate used which completely collapsed LIY.…”

Section: Discussionmentioning

confidence: 98%

“…Alaska) stems and sunflower (Helianthus annuus L., cv. Odille, Pioneer) hypocotyls were isolated as previously described [3]. The protein con-*Corresponding author.…”

Section: Mitochondria Preparationmentioning

confidence: 99%

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ATP/ADP antiporter is involved in uncoupling of plant mitochondria induced by low concentrations of palmitate

1994

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Carboxyatractyloside partially restored the transmembrane electrical potential difference (d'p) dissipated by low concentrations of pahnitate in pea stem mitochondria. This effect was more marked when mitochondria from sunflower were assayed. It is sugeested that the A'WADP translocator is involved in the free fatty acid-induced uncoupling of oxidative phosphorylation in plant mitocdondria, o&when its level is sufficiently high and the concentration of the fatty acid is low to collapse only partially AY.

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Free fatty acids dissipate proton electrochemical gradients in pea stem microsomes and submitochondrial particles

Cited by 23 publications

References 32 publications

Unusual Low Proton Permeability of Liposomes Prepared from the Endogenous Myelin Lipids

Unusual Low Proton Permeability of Liposomes Prepared from the Endogenous Myelin Lipids

Hydrogen peroxide generation by higher plant mitochondria oxidizing complex I or complex II substrates

ATP/ADP antiporter is involved in uncoupling of plant mitochondria induced by low concentrations of palmitate

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