Search results for "DEHYDROGENASE COMPLEX"
showing 10 items of 20 documents
Effects of indole-3-acetic acid on Sinorhizobium meliloti survival and on symbiotic nitrogen fixation and stem dry weight production
2009
We evaluated the effects of the main auxin phytohormone, indole-3-acetic acid (IAA), on the central metabolism of Sinorhizobium meliloti strain 1021. We either treated the Sinorhizobium meliloti 1021 strain with 0.5 mM IAA (1021+) or use a derivative, RD64, of the same strain harbouring a pathway for IAA biosynthesis converting tryptophan into IAA via indoleacetamide. We assayed the activity of key enzymes in the major energy-yielding pathways (Entner-Doudoroff, Embden-Meyerhof-Parnas, pentose phosphate, glyoxylate bypass and tricarboxylic acid cycle). We found that activity of two main regulative tricarboxylic acid (TCA) cycle enzymes was increased. Citrate synthase (CS) activity, as compa…
Pyruvate kinase type M2: a crossroad in the tumor metabolome.
2002
Cell proliferation is a process that consumes large amounts of energy. A reduction in the nutrient supply can lead to cell death by ATP depletion, if cell proliferation is not limited. A key sensor for this regulation is the glycolytic enzyme pyruvate kinase, which determines whether glucose carbons are channelled to synthetic processes or used for glycolytic energy production. In unicellular organisms pyruvate kinase is regulated by ATP, ADP and AMP, by ribose 5-P, the precursor of the nucleic acid synthesis, and by the glycolytic intermediate fructose 1,6-P2 (FBP), thereby adapting cell proliferation to nutrient supply. The mammalian pyruvate kinase isoenzyme type M2 (M2-PK) displays the …
Pyruvate fermentation by Oenococcus oeni and Leuconostoc mesenteroides and role of pyruvate dehydrogenase in anaerobic fermentation.
2005
ABSTRACT The heterofermentative lactic acid bacteria Oenococcus oeni and Leuconostoc mesenteroides are able to grow by fermentation of pyruvate as the carbon source (2 pyruvate → 1 lactate + 1 acetate + 1 CO 2 ). The growth yields amount to 4.0 and 5.3 g (dry weight)/mol of pyruvate, respectively, suggesting formation of 0.5 mol ATP/mol pyruvate. Pyruvate is oxidatively decarboxylated by pyruvate dehydrogenase to acetyl coenzyme A, which is then converted to acetate, yielding 1 mol of ATP. For NADH reoxidation, one further pyruvate molecule is reduced to lactate. The enzymes of the pathway were present after growth on pyruvate, and genome analysis showed the presence of the corresponding st…
Natural substances (acetogenins) from the family Annonaceae are powerful inhibitors of mitochondrial NADH dehydrogenase (Complex I).
1994
Natural products from the plants of the family Annonaceae, collectively called Annonaceous acetogenins, are very potent inhibitors of the NADH-ubiquinone reductase (Complex I) activity of mammalian mitochondria. The properties of five of such acetogenins are compared with those of rotenone and piericidin, classical potent inhibitors of Complex I. Rolliniastatin-1 and rolliniastatin-2 are more powerful than piericidin in terms of both their inhibitory constant and the protein-dependence of their titre in bovine submitochondrial particles. These acetogenins could be considered therefore the most potent inhibitors of mammalian Complex I. Squamocin and otivarin also have an inhibitory constant …
Role of Reduced Lipoic Acid in the Redox Regulation of Mitochondrial Aldehyde Dehydrogenase (ALDH-2) Activity
2007
Chronic therapy with nitroglycerin results in a rapid development of nitrate tolerance, which is associated with an increased production of reactive oxygen species. We have recently shown that mitochondria are an important source of nitroglycerin-induced oxidants and that the nitroglycerin-bioactivating mitochondrial aldehyde dehydrogenase is oxidatively inactivated in the setting of tolerance. Here we investigated the effect of various oxidants on aldehyde dehydrogenase activity and its restoration by dihydrolipoic acid. In vivo tolerance in Wistar rats was induced by infusion of nitroglycerin (6.6 microg/kg/min, 4 days). Vascular reactivity was measured by isometric tension studies of iso…
Interaction of the mitochondrial membrane D-3-hydroxybutyrate dehydrogenase with fluorescent phospholipids
1993
Norbert Latruffe l ,I, Boubker Nasser ‘, Claude Morpain 3, Jiirgen Zirkel 4, Michael Seiter 4, Bernard Laude 3 and Wolfgang Trommer 4 ’ Laboratoire de Biobgie Mol&laire et Cellulaire, Universite’ de Bourgogne, Fact& des Sciences Mirande, BP 138, 21004 D@on Cedex (France) 2 Laboratoire de Biochimie &A CNRS 531) and 3 Laboratoire de Chimie Organique, Universite’ de Franche-Comte 25030 Besaqon Cedex (France) 4 Fachbereich Chemie, Universitiit Kaiserslautem, D 6750 Kaiserslautem (Germany)
Simulation of Metabolism for The Calculation of Enzyme Activities in Stress Metabolism
1988
Abstract Using data of indirect calorimetry, total energy turnover as well as the rate of combustion of carbohydrates, fat and amino acids can be calculated. For the evaluation, simple standard procedures (4) are used. These procedures presume, that several assumptions are satisfied, e.g. a complete degradation of the energy delivering substrates and undisturbed enzyme activities. To be able to interprete also measurements, which are performed in the post-traumatic state as well as for estimation of the extent and consequences of reduced enzyme activities, a new method for the simulation of metabolism was developed. Hie underlying model considers a reduced activity of key enzymes and a swit…
Nitrate Reductase Activity of Mitochondrial Aldehyde Dehydrogenase (ALDH-2) as a Redox Sensor for Cardiovascular Oxidative Stress
2009
In 2002, mitochondrial aldehyde dehydrogenase (ALDH-2) was identified as an organic nitrate bioactivating enzyme. This so-called nitrate reductase activity denitrates nitroglycerin (glycerol trinitrate) to its 1,2-glycerol dinitrate metabolite and nitrite. This reaction relies on reduced thiols at the active site of the enzyme and on the presence of reduced dithiols as the electron source. During bioconversion of nitroglycerin, and also in the presence of reactive oxygen and nitrogen species, the active site thiols of ALDH-2 are oxidized and the enzyme looses its activity. We, therefore, speculated that ALDH-2 activity could be a useful marker for cardiovascular oxidative stress. Indeed, th…
Effects of high-fat diet and physical activity on pyruvate dehydrogenase kinase-4 in mouse skeletal muscle
2012
Abstract Background The expression of PDK4 is elevated by diabetes, fasting and other conditions associated with the switch from the utilization of glucose to fatty acids as an energy source. It is previously shown that peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a master regulator of energy metabolism, coactivates in cell lines pyruvate dehydrogenase kinase-4 (PDK4) gene expression via the estrogen-related receptor α (ERRα). We investigated the effects of long-term high-fat diet and physical activity on the expression of PDK4, PGC-1α and ERRα and the amount and function of mitochondria in skeletal muscle. Methods Insulin resistance was induced by a high-fat (HF) d…
Branched-Chain Amino Acid Deprivation Decreases Lipid Oxidation and Lipogenesis in C2C12 Myotubes
2022
Impaired lipid metabolism is a common risk factor underlying several metabolic diseases such as metabolic syndrome and type 2 diabetes. Branched-chain amino acids (BCAAs) that include valine, leucine and isoleucine have been proven to share a role in lipid metabolism and hence in maintaining metabolic health. We have previously introduced a hypothesis suggesting that BCAA degradation mechanistically connects to lipid oxidation and storage in skeletal muscle. To test our hypothesis, the present study examined the effects of BCAA deprivation and supplementation on lipid oxidation, lipogenesis and lipid droplet characteristics in murine C2C12 myotubes. In addition, the role of myotube contract…