Search results for "respiratory chain"
showing 10 items of 96 documents
Mitochondrial myopathy with lactic acidosis and deficient activity of muscle succinate cytochrome-c-oxidoreductase
1984
A male infant had severe muscular hypotonia from birth. Recurrent vomiting with dehydration and severe metabolic acidosis complicated the course. Elevated lactate (up to 12.3 mmol/l; n less than 2), pyruvate (0.4 mmol/l; n less than 0.05) and alanine levels were found in serum with an abnormal lactate/pyruvate ratio (greater than 30; n less than 15). In urine the concentrations of lactate, pyruvate, alanine and of several intermediates of the citric acid cycle were increased. In muscle, numerous disseminated "ragged red fibres" were found by light microscopy; muscle fibres were found to contain subsarcolemmal aggregates of mitochondria, lipid droplets and glycogen by electromicroscopical me…
Polymeric Oriented Monolayers and Multilayers as Model Surfaces
1985
All living cells are surrounded by a lipid bilayer membrane in which a variety of proteins (e.g., enzymes) are embedded (fluid mosaic model; Figure 1). Phospholipids and cholesterol represent the major part of the lipids of a biomembrane. Figure 2 illustrates the structure of some typical amphiphilic membrane components with hydrophobic alkyl chains and hydrophilic head groups. The amount of protein in biological membranes varies between 40 and 60%(3); however, in highly specialized membranes values between 20% (myelin sheath of nerve axons; electrical isolator) and 75% (mitochondrial inner membrane; enzyme system of the respiratory chain) may occur. Furthermore, the incorporation of protei…
The Low Energy-Coupling Respiration in Zymomonas mobilis Accelerates Flux in the Entner-Doudoroff Pathway.
2015
Performing oxidative phosphorylation is the primary role of respiratory chain both in bacteria and eukaryotes. Yet, the branched respiratory chains of prokaryotes contain alternative, low energy-coupling electron pathways, which serve for functions other than oxidative ATP generation (like those of respiratory protection, adaptation to low-oxygen media, redox balancing, etc.), some of which are still poorly understood. We here demonstrate that withdrawal of reducing equivalents by the energetically uncoupled respiratory chain of the bacterium Zymomonas mobilis accelerates its fermentative catabolism, increasing the glucose consumption rate. This is in contrast to what has been observed in o…
Zymomonas mobilis metabolism: Novel tools and targets for its rational engineering
2020
Abstract Zymomonas mobilis is an α-proteobacterium that interests the biofuel industry due to its perfect ethanol fermentation yields. From its first description as a bacterial isolate in fermented alcoholic beverages to date, Z. mobilis has been rigorously studied in directions basic and applied. The Z. mobilis powerful Entner-Doudoroff glycolytic pathway has been the center of rigorous biochemical studies and, aside from ethanol, it has attracted interest in terms of high-added-value chemical manufacturing. Energetic balances and the effects of respiration have been explored in fundamental directions as also in applications pursuing strain enhancement and the utilization of alternative ca…
Improvement of acetaldehyde production in Zymomonas mobilis by engineering of Its aerobic metabolism
2019
Acetaldehyde is a valuable product of microbial biosynthesis, which can be used by the chemical industry as the entry point for production of various commodity chemicals. In ethanologenic microorganisms, like yeast or the bacterium Zymomonas mobilis, this compound is the immediate metabolic precursor of ethanol. In aerobic cultures of Z. mobilis, it accumulates as a volatile, inhibitory byproduct, due to the withdrawal of reducing equivalents from the alcohol dehydrogenase reaction by respiration. The active respiratory chain of Z. mobilis with its low energy-coupling efficiency is well-suited for regeneration of NAD+ under conditions when acetaldehyde, but not ethanol, is the desired catab…
Mitochondrial involvement in non-alcoholic steatohepatitis
2007
Non-alcoholic steatohepatitis (NASH) is an increasing recognized condition that may progress to end-stage liver disease. There are consistent evidences that mitochondrial dysfunction plays a central role in NASH whatever its origin. Mitochondria are the key controller of fatty acids removal and this is part of an intensive gene program that modifies hepatocytes to counteract the excessive fat storage. Mitochondrial dysfunction participates at different levels in NASH pathogenesis since it impairs fatty liver homeostasis and induces overproduction of ROS that in turn trigger lipid peroxidation, cytokines release and cell death. In this review we briefly recall the role of mitochondria in fat…
Oxidant antioxidants and adaptive responses to exercise.
2015
The extensive damage produced by unaccustomed (acute) exercise and the health benefits of regular physical activity are well-known phenomena as well as the role played in them by reactive oxygen species (ROS). The present issue reports some interesting studies showing that the Janus faced effects of exercise-induced ROS in skeletal muscle. Most studies dealing with ROS contribution to acute exercise-induced tissue damage determine the levels of markers of oxidative damage to specific substances but they do not take into account total redox status of an individual before and after exercise. In their research article D. Stagos et al. used markers measuring plasma static (sORP) and capacity (c…
Reactive oxygen species derived from the mitochondrial respiratory chain are not responsible for the basal levels of oxidative base modifications obs…
2004
The mitochondrial electron transport chain (ETC) is the most important source of reactive oxygen species (ROS) in mammalian cells. To assess its relevance to the endogenous generation of oxidative DNA damage in the nucleus, we have compared the background (steady-state) levels of oxidative DNA base modifications sensitive to the repair glycosylase Fpg (mostly 7,8-dihydro-8-oxoguanine) in wild-type HeLa cells and HeLa rho0 cells. The latter are depleted of mitochondrial DNA and therefore are unable to produce ROS in the ETC. Although the levels of ROS measured by flow cytometry and redox-sensitive probes in rho0 cells were only 10-15% those of wild-type cells, steady-state levels of oxidativ…
Nitroglycerine causes mitochondrial reactive oxygen species production: In vitro mechanistic insights
2007
Background Nitroglycerine (GTN) is an organic nitrate that has been used for more than 100 years. Despite its widespread clinical use, several aspects of the pharmacology of GTN remain elusive. In a recent study, the authors of the present study showed that GTN causes opening of the mitochondrial permeability transition pore (mPTP) and mitochondrial production of reactive oxygen species (ROS). Objective In the present study, it was tested whether GTN-induced ROS production depends on mitochondrial potassium ATP-dependent channel or mPTP opening, and/or GTN biotransformation. Methods and results Isolated rat heart mitochondria were incubated with succinate (a substrate for complex II) and GT…
Mitochondrially encoded cysteine predicts animal lifespan
2007
Summary The role of genetic factors in the determination of lifespan is undisputed. However, numerous successful efforts to identify individual genetic modulators of longevity have not yielded yet a quantitative measure to estimate the lifespan of a species from scratch, merely based on its genomic constitution. Here, we report on a meta-examination of genome sequences from 248 animal species with known maximum lifespan, including mammals, birds, fish, insects, and helminths. Our analysis reveals that the frequency with which cysteine is encoded by mitochondrial DNA is a specific and phylogenetically ubiquitous molecular indicator of aerobic longevity: long-lived species synthesize respirat…