Search results for "keto acid"
showing 8 items of 8 documents
A detailed identification study on high-temperature degradation products of oleic and linoleic acid methyl esters by GC–MS and GC–FTIR
2012
GC-MS and GC-FTIR were complementarily applied to identify oxidation compounds formed under frying conditions in methyl oleate and linoleate heated at 180ºC. The study was focused on the compounds that originated through hydroperoxide scission that remain attached to the glyceridic backbone in fats and oils and form part of non-volatile molecules. Twenty one short-chain esterified compounds, consisting of 8 aldehydes, 3 methyl ketones, 4 primary alcohols, 5 alkanes and 1 furan, were identified. In addition, twenty non-esterified volatile compounds, consisting of alcohols, aldehydes and acids, were also identified as major non-esterified components. Furanoid compounds of 18 carbon atoms form…
Double-blind cross-over study with oral alpha-ketoacids in patients with chronic renal failure.
1980
In 15 ambulatory patients with renal insufficiency (creatinine clearance, 9.9 +/- 3.0 ml/min) the effect of oral supplementation with alpha-ketoacids has been compared with that of placebo. The protein intake amounted to 0.55 g protein per kilogram body weight of high biological value, as estimated by dietary recordings. After a control period of 3 months the patients received, in a double-blind study, 1.05 g alpha-ketoacids/10 kg body weight per day or a placebo for 6 weeks with a subsequent cross-over. Fasting blood samples were analyzed at 3-week intervals for routine laboratory parameters and 17 proteins. Anthropometric and clinical data have been recorded every 3 weeks. While therapy w…
Reaction pathways of glucose oxidation by ozone under acidic conditions.
2009
The ozonation of d-glucose-1-(13)C, 2-(13)C, and 6-(13)C was carried out at pH 2.5 in a semi-batch reactor at room temperature. The products present in the liquid phase were analyzed by GC-MS, HPAEC-PAD, and (13)C NMR spectroscopy. Common oxidation products of glucose have also been submitted to identical ozonation conditions. For the first time, a pentaric acid was identified and its formation quantitatively correlated to the loss of C-6 of glucose in the form of carbon dioxide. Potential mechanisms for the formation of this pentaric acid are discussed. The well-accepted pathway involving the anomeric position in glucose, gluconic acid, arabinose, and carbon dioxide is reinvestigated. The …
Enzymatic and pharmacokinetic studies on the metabolism of branched chain alpha-keto acids in the rat.
1983
Michaelis-constants and enzyme activities for dehydrogenation and transamination of the three branched chain alpha-keto acids in liver, kidney, skeletal muscle, and brain of rats are reported. After oral load only 11-22% of the keto acids pass the liver unchanged. Blood levels in pharmacokinetic and absorption studies are related to the Michaelis-constants. At the low keto-acid concentrations after oral application, dehydrogenation in the non-hepatic tissues is supposed to prevail over transamination. Data on feed efficiency of branched chain alpha-keto acids reported in the literature support this view. The chance for transamination is better after intravenous administration. The transfera…
Influence of carboxylic acids on the stereospecific nicotinamide adenine dinucleotide-dependent and nicotinamide adenine dinucleotide-independent lac…
1971
Leuconostoc mesenteroides increased its lactic acid production from glucose threefold when malic acid was added to the culture. This increase resulted also in a reduction of the ratio of d -lactic acid to l -lactic acid (31.5 to 1.23). Addition of malic acid increased 6.5-fold the specific activity of nicotinamide adenine dinucleotide (NAD)-linked l -lactate dehydrogenase and increased 3.2-fold that of NAD-linked d -lactate dehydrogenase. The Michaelis constant ( K m ) for NAD of the NAD-linked l -lactate dehydrogenase increased with the addition of malate, but no change was observed in the K m values for the respective d -enzyme. The effect of carboxylic acids on the NAD-linked l -lactate…
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)
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…