Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “OXIDATIVE PHOSPHORYLATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,279 records · Page 71Linked to original sources
PubMed2003

Temperature dependence of rat liver mitochondrial respiration with uncoupling of oxidative phosphorylation by fatty acids. Influence of inorganic phosphate.

The respiration rate of liver mitochondria in the course of succinate oxidation depends on temperature in the presence of palmitate more strongly than in its absence (in state 4). In the Arrhenius plot, the temperature dependence of the palmitate-induced stimulation of respiration has a bend at 22 degrees C which is characterized by transition of the activation energy from 120 to 60 kJ/mol. However, a similar dependence of respiration in state 4 is linear over the whole temperature range and corresponds to the activation energy of 17 kJ/mol. Phosphate partially inhibits the uncoupling effect of palmitate. This effect of phosphate is increased on decrease in temperature. In the presence of phosphate the temperature dependence in the Arrhenius plot also has a bend at 22 degrees C, and the activation energy increases from 128 to 208 kJ/mol in the range from 13 to 22 degrees C and from 56 to 67 kJ/mol in the range from 22 to 37 degrees C. Mersalyl (10 nmol/mg protein), an inhibitor of the phosphate carrier, similarly to phosphate, suppresses the uncoupling effect of laurate, and the effects of mersalyl and phosphate are not additive. The recoupling effects of phosphate and mersalyl seem to show involvement of the phosphate carrier in the uncoupling effect of fatty acids in liver mitochondria. Possible mechanisms of involvement of the phosphate carrier in the uncoupling effect of fatty acids are discussed.

2,4-Dinitrophenol↗
PubMed2002

Mutated human SOD1 causes dysfunction of oxidative phosphorylation in mitochondria of transgenic mice.

A growing body of evidence suggests that impaired mitochondrial energy production and increased oxidative radical damage to the mitochondria could be causally involved in motor neuron death in amyotrophic lateral sclerosis (ALS) and in familial ALS associated with mutations of Cu,Zn superoxide dismutase (SOD1). For example, morphologically abnormal mitochondria and impaired mitochondrial histoenzymatic respiratory chain activities have been described in motor neurons of patients with sporadic ALS. To investigate further the role of mitochondrial alterations in the pathogenesis of ALS, we studied mitochondria from transgenic mice expressing wild type and G93A mutated hSOD1. We found that a significant proportion of enzymatically active SOD1 was localized in the intermembrane space of mitochondria. Mitochondrial respiration, electron transfer chain, and ATP synthesis were severely defective in G93A mice at the time of onset of the disease. We also found evidence of oxidative damage to mitochondrial proteins and lipids. On the other hand, presymptomatic G93A transgenic mice and mice expressing the wild type form of hSOD1 did not show significant mitochondrial abnormalities. Our findings suggest that G93A-mutated hSOD1 in mitochondria may cause mitochondrial defects, which contribute to precipitating the neurodegenerative process in motor neurons.

Animals↗
PubMed1996

Effects of Ca2+ on oxidative phosphorylation in mitochondria from the thermogenic organ of marlin.

Mitochondria from the muscle-derived thermogenic (heater) organ and oxidative red muscle of the blue marlin (Makaira nigricans) were studied in order to evaluate aspects of the mechanism of thermogenesis in heater tissue. We investigated whether short-term Ca(2+)-induced uncoupling of mitochondria contributes to the thermogenic cycle of the heater organ by enhancing the respiration rate. Specific electrodes were used to obtain simultaneous measurements of oxygen consumption and Ca2+ fluxes on isolated mitochondria, and the effects of various concentrations of Ca2+ on respiration rates and the ADP phosphorylated/atomic oxygen consumed (P/O) ratio were examined. Addition of Ca2+ in excess of 10 mumol l-1 to respiring heater organ or red muscle mitochondria partially inhibited state 3 respiration and reduced the P/O ratio, indicating that the mitochondria were partially uncoupled. These effects were blocked by 2 mumol l-1 Ruthenium Red. In heater organ mitochondria, state 3 respiration rate and the P/O ratio were not significantly reduced by 1 mumol l-1 free Ca2+, a concentration likely to be near the maximum achieved in a stimulated cell. This indicates that transient increases in cytosolic Ca2+ concentration may not significantly reduce the P/O ratio of heater organ mitochondria. The activity of 2-oxoglutarate dehydrogenase in heater organ mitochondria was stimulated by approximately 15% by Ca2+ concentrations between 0.2 and 1 mumol l-1. These results suggest that heater organ mitochondria are able to maintain a normal P/O ratio and should maintain ATP output during transient increases in Ca2+ concentration, supporting a model in which an ATP-consuming process drives thermogenesis. Activation of mitochondrial dehydrogenases by low levels of Ca2+ may also enhance respiration and contribute to thermogenesis.

Adenosine Diphosphate↗
PubMed2001

Effects of phenobarbital on activity of mitochondrial enzymes in peripheral blood lymphocytes and oxidative phosphorylation in liver mitochondria.

Treatment with phenobarbital (30 mg/kg) for 2 weeks increased succinate dehydrogenase activity in peripheral blood lymphocytes of male rats. In 38% phenobarbital-treated rats succinate-cytochrome c oxidoreductase activity was lower than in the control due to accumulation of cells exhibiting no enzyme activity; in 44% animals this parameter was higher than in the control. The rates of state 3 respiration (oxidation substrate succinate), phosphorylation, and uncoupled respiration in liver mitochondria (oxidation substrate glutamate/malate mixture) increased after 35-day treatment with phenobarbital. The respiratory control and ADP/O ratio for these substrates did not differ from the control.

Animals↗
PubMed2000

Activation of p38 kinase links tau phosphorylation, oxidative stress, and cell cycle-related events in Alzheimer disease.

The temporal association between oxidative stress and the hallmark pathologies of Alzheimer disease (AD) demonstrates that oxidative stress is among the earliest events in the disease. Nonetheless, neither the consequences of oxidative stress nor how oxidative stress relates to other pathological features of the disease are clear at this point. To begin to address these issues, we investigated p38 kinase, which is induced by oxidative stress, in the pathogenesis of AD. In hippocampal and cortical brain regions of individuals with AD, p38 is exclusively localized in association with neurofibrillar pathology. By marked contrast, these brain regions exhibit a low level of diffuse p38 staining in the neuronal cytoplasm in controls. We found a complete overlap of the immunostaining profiles of p38 and tau-positive neurofibrillary pathology and that the majority of p38 was activated in AD neurons, both of which support an association of p38 with the disease process. Moreover, the finding that PHF-tau co-immunoprecipitates with p38, and that p38 co-purifies with PHF-tau, strongly suggests that they are physically associated in vivo. Since p38 is also implicated in cell cycle regulation, our findings provide a link between the cell cycle re-entrant phenotype, cytoskeletal phosphorylation and oxidative stress in AD.

Aged↗