Conservation and transformation of energy by bacterial membranes.

Harold, Franklin M.

doi:10.1128/mmbr.36.2.172-230.1972

Cited by 433 publications

(176 citation statements)

References 236 publications

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“…It is well established now that a large number of bacterial transport systems derive their energy from the proton electrochemical gradient, the protonmotive force, which is generated by proton pumps as was suggested by Mitchell [1][2][3]. Ap = ~ = AxI, -ZpH where Z = 2.3 RT/F (1) The mechanism suggested by Mitchell for these systems [1,4] is a coupling between the spontaneous uptake of protons and the non-spontaneous uptake of the substrate by a specific carrier.…”

Section: Introductionmentioning

confidence: 99%

The driving force for proton(s) metabolites cotransport in bacterial cells

Rottenberg

1976

FEBS Letters

102

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Section: Introductionmentioning

confidence: 99%

The driving force for proton(s) metabolites cotransport in bacterial cells

Rottenberg

1976

FEBS Letters

102

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“…This view was supported by the following evidence. Addition of nigericin to membrane vesicles energized by ATP discharged the proton gradient by K+/H + exchange [7] curve 1). However, nigericin ( fig.2, curves 2,3) and the uncoupler carbonyl cyanide m-chlorophenylhydrazone (not shown) had no effect on the increase in the fluorescence of NPN which occurred after substrate oxidation had removed all the oxygen from the medium.…”

Section: Resultsmentioning

confidence: 99%

The fluorescence intensity of the lipophilic probe N‐phenyl‐1‐naphthylamine responds to the oxidation‐reduction state of the respiratory chain in everted membrane vesicles of Escherichia coli

Sedgwick

Bragg

1987

FEBS Letters

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N-Phenyl-l-naphthylamine (NPN), a reagent which has been used previously to probe the fluidity or microviscosity of the membrane lipids of intact cells of Escherichia coli, was found to respond to metabolic changes in everted inner membrane vesicles from this organism. NPN was bound to the vesicles to produce a steady-state level of fluorescence intensity. Addition of substrate or ATP did not alter the fluorescence. However, following complete removal of oxygen from the medium by oxidation of substrate through the respiratory chain, there was an increase in the fluorescence of NPN. Reoxidation of the components of the respiratory chain by the addition of oxygen, ferricyanide, fumarate or nitrate decreased fluorescence to the steady-state level until the oxidant had been completely reduced. The fluorescence changes were insensitive to the state of energization of the membrane. It is proposed that NPN responds to the state of reduction of components of the respiratory chain either directly by reacting with a component of the chain or indirectly through an effect transmitted to the membrane by a change in the conformation of respiratory chain components.

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“…The demonstration of dihydrolipoate dependent ATP synthesis by promitochondria raises the question as to whether the reaction is of metabolic significance in the anaerobic yeast cell. Reduction of lipoate by a suitable dehydrogenase or flavoprotein-linked dehydrogenase coupled to an acceptor such as fumarate is a possible ATP generating system and similar reactions are of major metabolic significance in anaerobic bacteria where the membrane ATPase has been assumed to have a proton pumping function only [9]. A possible role for ATP-generating reactions in promitochondria and in yeast 'petite' mitochondria has been discussed by Kovac [lo] on the basis of sensitivity to inhibitors and studies of cytochrome de& cient mutants.…”

Section: Discussionmentioning

confidence: 99%