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Results for “electron transport chain”

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At least 19 recordsLinked to original sources
PubMedDate not supplied

[Functional characteristics of the electron transport chain in Candida mycoderma yeasts exposed to benzhydroxamic acid].

The effect of antimycin A and benzhydroxamic acid (BHA) on functioning of the electron transport system was studied with the resting cells of Candida mycoderma grown in a medium containing glucose and collected at the beginning of the deceleration phase. In the original ("control") cells, the processes of oxygen consumption were shown to be mediated mainly by the phosphorylating electron transport chain. When the cells were incubated withe glucose, the cyanide resistant electron transport chain (CRETC) started to operate in these processes. Antimycin A stimulated the operation of CRETC. BHA blocked CRETC and, at the same time, prevented the participation of pyridine nucleotides (PN) in the processes of oxygen utilization. Apparently, electron donors (or reduced equivalents) in the electron transport chain were flavin enzymes operating in the cytochrome b region of the chain instead of PN. Similar changes in the electron transport system (when PN were not involved in the processes of oxygen utilization) were observed if resting cells were incubated in the presence of ethanol.

Antimycin A↗
PubMed1978

On the site of function of the Rieske iron-sulfur center in the chloroplast electron transport chain.

A photosynthetic mutant (strain 1073) of Lemna perpusilla was previously shown to have a block in the electron transport chain between plastoquinone and cytochrome f ((1976) Plant Physiol. 57, 577--579). Electron paramagnetic resonance analysis of chloroplasts from this mutant indicates that the g = 1.89 signal of a reduced iron-sulfur center (the 'Rieske' iron-sulfur center) is absent. The absence of this signal indicates the Rieske center is either absent from or defective in the mutant, and this result is consistent with this iron-sulfur center functioning between plastoquinone and cytochrome f in the electron transport chain of chloroplasts.

Binding Sites↗
PubMedDate not supplied

[Changes in the electron transport chain in Escherichia coli depending on the cultivation conditions and growth phase].

Changes in the electron transport chain of E. coli K-12 were studied as a function of the growth phase and the nature of a terminal electron acceptor in the growth medium. The content of flavins in the preparations of bacterial membranes hardly changed in all cases. The highest concentration of quinones was observed in the bacterial membranes at the stationary growth phase under anaerobic conditions of growth in the presence of nitrate. These membranes contained also the greatest amount of cytochrome beta1. The concentration of cytochrome alpha2 in all the membranes was low and varied among different preparations. All the membranes contained a CO-binding pigment whose content was maximal in the membranes of "nitrate" cells. The membranes of cells grown under aerobic conditions oxidized malate, apart from NADH and lactate, whereas the membranes of cells cultivated under anaerobic conditions in the presence of nitrate oxidized formiate. In most cases, the oxidase activity of the membranes of cells collected at the stationary growth phase was higher cf. the exponential phase.

Aerobiosis↗
PubMed1978

[Role of lipids in the function of microsomal electron transport chains of potato].

Microsomal membranes from potato tubers were extracted by acetone solutions of increasing concentrations (5, 10, 15, 20, 30, 40, 50, 70 and 90 p. cent). Microsomal lipids were progressively extracted: acetone concentrations exceeding 30 p. cent extracted large amounts of membraneous phospholipids (figure). Lipid extraction reduced NADH-cytochrome c reductase activity but did not affect NADH-ferricyanide reductase and NADPH-cytochrome c reductase activities. This was confirmed by experiments using increasing concentrations of sodium deoxycholate. After lipid extraction with acetone (or solubilization by triton X100), NADH-cytochrome c reductase activity of microsomal membranes could not be recovered by adding back lipids under various experimental conditions. These results strongly suggest that, in potato microsomes, lipids are undispensable components of the electron transport chain starting from NADH especially in the portion involving cytochrome b5. On the contrary, the second microsomal electron transport chain, starting from NADPH, is not regulated by lipids. However, plant microsomal membranes would be much more disturbed by liped extraction than animal microsomes and suitable relipidation conditions remain to be found to prove definitely the lipid dependence of plant microsomal electron transport.

Deoxycholic Acid↗
PubMed1979

[Protein carriers of the electron transport chain of non-photosynthesizing mutants of Chlamydomonas reinhardii].

The amounts of ferredoxin, plastocyanin, ferredoxin-NADP-reductase were determined by electrophoresis and differential spectroscopy. The cytochrome levels in the chloroplasts of non-photosynthesizing mutants Chlamydomonas reinhardii were determined both in active and inactive photosystems. It was shown that the loss of PS-1 activity did not affect the amount and activity of the electron carriers. The disturbances of the donor side of PS-2 in the mutants were accompanied by a loss of the reaction center activity and by a decrease of cytochrome b599. The amounts of other protein components in the mutants with inactive PS-2 remained unchanged. The disturbances in the cytochrome c553 content presumably blocked the electron transfer between the photosystems but did not affect the activity of the reaction centers of PS and the levels of other carriers of the chloroplast electron transport chain.

Chlamydomonas↗
PubMedDate not supplied

[Establishment of the site of electron transport chain disruption in mutant Chlamydomonas chloroplasts with an inactive photosystem 2].

It has been shown in the studies of 6 strains of non-synthesizing Chlamydomonas reinhardi mutants with a damaged electron-transport chain (ETC) in the region of the Photosystem 2 (PS 2) that the damage is localized on the oxidizing side of PS 2. The ESR studies of the mutants have shown that signal 2 is absent in all the mutants, the width of signal 1 in some mutants is lower than in the control, which is, probably, concerned with the differences in the reaction centre structures. The ETC region from electron inlet from the donor--diphenylcarbaside to P700 is capable of functioning. It is suggested that in all the mutants studied the complex responsible for photodissociation of water is damaged.

2,6-Dichloroindophenol↗
PubMed1978

Sequence of b cytochromes relative to ubiquinone in the electron transport chain of Escherichia coli.

A ubiquinone-deficient mutant, carrying mutations in two genes affecting ubiquinone biosynthesis, has been used, in comparison with a normal strain, to determine the sequence of some of the components of the electron transport chain of Escherichia coli. The amounts of cytochromes reduced during aerobic steady-state conditions were estimated by comparing low-temperature difference spectra of normal or ubiquinone-deficient membranes with either D-lactate or reduced nicotinamide adenine dinucleotide as substrate. From the amounts of cytochromes reduced it was concluded that ubiquinone functions at two sites, one site being between the dehydrogenases and cytochromes and the second site being after cytochromes b562 and b556 but before cytochromes b558, d, and o. The scheme proposed is discussed in relation to the Mitchell protonmotive ubiquinone cycle.

Aerobiosis↗
PubMed1975

Effects of sulphate-limited growth in continuous culture on the electron-transport chain and energy conservation in Escherichia coli K12.

Growth of Escherichia coli K12 in a chemostat was limited by sulphate concentrations lower than 300 muM. The synthesis of extracellular polysaccharide and a change in morphology accompanied sulphate-limited growth. Growth yields with respect to the amount of glycerol or oxygen consumed were sixfold and twofold lower respectively under these conditions than when growth was limited by glycerol. Sulphate-limited cells lacked the proton-translocating oxidoreduction segment of the electron-transport chain between NADH and the cytochromes, and particles prepared from these cells lacked the energy-dependent reduction of NAD+ by succinate, DL-alpha-glycerophosphate or D-lactate, suggesting the loss of site-I phosphorylation. Glycerol-limited cells contained cytochrome b556, b562 and o, ubiquinone and low concentrations of menaquinone. Sulphate limitation resulted in the additional synthesis of cytochromes d, a1, b558 and c550; the amount of ubiquinone was decreased and menaquinone was barely detectable. Non-haem iron and acid-labile sulphide concentrations were twofold lower in electron-transport particles prepared from sulphate-limited cells. Recovery of site-I phosphorylation could not be demonstrated after incubating sulphate-limited cells with or without glycerol, in either the absence or presence of added sulphate. The loss of site-I phosphorylation in sulphate-limited cells is discussed with reference to the accompanying alterations in cytochrome composition of such cells. Schemes are proposed for the functional organization of the respiratory chains of E. coli grown under conditions of glycerol or sulphate limitation.

Cytochromes↗