Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.1.1.37 (malate dehydrogenase)
 4,591 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ubiquinol-1 in aerated aqueous solution inactivates several enzymes--alanine aminotransferase, alkaline phosphatase, Na+/K(+)-ATPase, creatine kinase and glutamine synthetase--but not isocitrate dehydrogenase and malate dehydrogenase. Ubiquinone-1 and/or H2O2 do not affect the activity of alkaline phosphatase and glutamine synthetase chosen as model enzymes. Dioxygen and transition metal ions, even if in trace amounts, are essential for the enzyme inactivation, which indeed does not occur under argon atmosphere or in the presence of metal chelators. Supplementation with redox-active metal ions (Fe3+ or Cu2+), moreover, potentiates alkaline phosphatase inactivation. Since catalase and peroxidase protect while superoxide dismutase does not, hydrogen peroxide rather than superoxide anion seems to be involved in the inactivation mechanism through which oxygen active species (hydroxyl radical or any other equivalent species) are produced via a modified Haber-Weiss cycle, triggered by metal-catalyzed oxidation of ubiquinol-1. The lack of efficiency of radical scavengers and the almost complete protection afforded by enzyme substrates and metal cofactors indicate a 'site-specific' radical attack as responsible for the oxidative damage.
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PMID:Enzyme inactivation by metal-catalyzed oxidation of coenzyme Q1. 135 46

When plant tissue extracts are electrophoresed on polyacrylamide gels and the gels are stained for malate dehydrogenase by the standard NAD-dependent dehydrogenase reaction, terminating in the formation of reduced Nitroblue Tetrazolium (NBT), achromatic bands, in addition to the expected chromatic bands, are observed. The achromatic bands are seen when the staining conditions favor a generalized background staining of the gel and have been shown, in a previous study, to be caused by peroxidase isozymes [1]. The present study examined the mechanism by which peroxidase produced the achromatic bands using horseradish peroxidase (HRP). The generalized background staining resulted from the phenazine methosulfate (PMS)-mediated reduction of NBT. This reduction was enhanced by H2O2 and suppressed by HRP. Peroxidase apparently catalyzes the peroxidative oxidation of reduced PMS, which suppresses the generalized reduction of NBT in gel regions containing peroxidase isozymes producing the achromatic bands. In contrast, however, HRP also appears to catalyze the peroxidative oxidation of reduced NAD, but this reaction increases the reduction of NBT. The results are discussed in the context of the mechanisms proposed by others for the PMS-mediated reduction of NBT and for the peroxidase-catalyzed NADH-dependent formation of H2O2. This peroxidase-catalyzed reaction has been proposed for the plant peroxidases involved in lignification.
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PMID:An explanation of the achromatic bands produced by peroxidase isozymes in polyacrylamide electrophoresis gels stained for malate dehydrogenase. 137 53

Anaerobically induced NAD-linked glycerol dehydrogenase of Klebsiella pneumoniae for fermentative glycerol utilization was reported previously to be inactivated in the cell during oxidative metabolism. In vitro inactivation was observed in this study by incubating the purified enzyme in the presence of O2, Fe2+, and ascorbate or dihydroxyfumarate. It appears that O2 and the reducing agent formed H2O2 and that H2O2 reacted with Fe2+ to generate an activated species of oxygen which attacked the enzyme. The in vitro-oxidized enzyme, like the in vivo-inactivated enzyme, showed an increased Km for NAD (but not glycerol) and could no longer be activated by Mn2+ which increased the Vmax of the native enzyme but decreased its apparent affinity for NAD. Ethanol dehydrogenase and 1,3-propanediol oxidoreductase, two enzymes with anaerobic function, also lost activity when the cells were incubated aerobically with glucose. However, glucose 6-phosphate dehydrogenase (NADP-linked), isocitrate dehydrogenase, and malate dehydrogenase, expected to function both aerobically and anaerobically, were not inactivated. Thus, oxidative modification of proteins in vivo might provide a mechanism for regulating the activities of some anaerobic enzymes.
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PMID:Inactivation of glycerol dehydrogenase of Klebsiella pneumoniae and the role of divalent cations. 390 46

Physiological concentrations [< 11 mM] of formate do not violate the metabolism of S. bovis and M. elsdenii. A significant inhibition is caused by concentrations of 22 and 44 mM. In this case the process of ammonia formation in S. bovis is inhibited more pronouncedly. Peculiar effects of formate (11 mM) on LDH, FDH, aconitase, isocitrate dehydrogenase, fumarase, L-MDH and malic-enzyme have been stated. The changes show that it enhances assimilation of sugars fermented to lactate in S. bovis, in contrast to M. elsdenii, where it activates the utilization of lactic acid. During the log-phase S. bovis utilized only 11.5% of [14C] H2O2, whereas M. elsdenii uses 33.4% of it. The major amount of the label is transferred from intracellular inclusions to nucleic acids (in S. bovis--74.7%, in M. elsdenii--87%) and then incorporated into low molecular substances (23.5 and 11.9%, respectively), the rest being incorporated into proteins and lipids.
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PMID:[Formate metabolism by lactate-producing and lactate-utilizing rumen bacteria]. 787 87

A developmental block is induced by phosphate in rat embryos at the late two-cell stage. The present study was designed to examine the energy metabolism of rat two-cell blocked and non-blocked embryos. Enzyme activity was measured in individual embryos by histochemical techniques. The activities of malate dehydrogenase, isocitrate dehydrogenase, lactate dehydrogenase, pyruvate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, glutamate dehydrogenase, glucose-6-phosphate dehydrogenase, glucose-6-phosphatase, and phosphorylase did not differ among non-blocked and blocked embryos. However, the activity of succinate dehydrogenase was significantly decreased in blocked embryos compared with non-blocked embryos. In blocked embryos, cytochrome oxidase activity was distributed homogeneously, but was located at the perinuclear region in non-blocked embryos. Active mitochondrial organization was visualized using the fluorescent probe rhodamine 123 and laser scanning confocal microscopy. In both non-blocked and blocked embryos, mitochondria were distributed homogeneously. The concentration of H2O2 measured fluorometrically in embryos cultured without phosphate did not change significantly during the culture period, but decreased in embryos cultured with phosphate. The timing corresponded to the occurrence of the two-cell block. In summary, these results suggest that the developmental block in rat two-cell embryos is induced by disturbance of mitochondrial energy metabolism.
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PMID:Microscopic analysis of enzyme activity, mitochondrial distribution and hydrogen peroxide in two-cell rat embryos. 986 Nov 63

Fluorescence microscopy was used to visualize the accumulated fluorescent product of the enzyme alkaline phosphatase to indicate where active covalently bound enzyme remained on the surface after application of a Nd: YAG laser interference pattern to a surface that was first globally derivatized with the covalently bound enzyme. The electrochemical kinetics of the same carbon fiber surface were examined through the electrogenerated chemiluminescence of Ru(bpy)(3)2+ to determine that electron-transfer sites were indeed segregated from the enzyme-binding sites. The enzyme-derivatized areas are determined to be separate and distinct from the areas of enhanced electron transfer. Two other enzymes, glucose oxidase and malic dehydrogenase, were then covalently bound to carbon fiber microelectrode surfaces in order to verify the change in detection limit of their respective cofactors, NADH or H2O2, under a variety of surface conditions. The S/N of an enzyme-modified electrode after laser interference pattern photoablation and electrocatalytic treatment is improved by more than 1 order of magnitude over that observed at an electrode that is globally enzyme modified.
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PMID:Laser interference pattern ablation of a carbon fiber microelectrode: biosensor signal enhancement after enzyme attachment. 1105 9

Activity of a number of enzymes related to lignin formation was measured in a Picea abies (L) Karsten suspension culture that is able to produce native-like lignin into the nutrient medium. This cell culture is an attractive model for studying lignin formation, as the process takes place independently of the complex macromolecular matrix of the native apoplast. Suspension culture proteins were fractionated into soluble cellular proteins, ionically and covalently bound cell wall proteins and nutrient medium proteins. The nutrient medium contained up to 5.3% of total coniferyl alcohol peroxidase (EC 1.11.1.7) activity and a significant NADH oxidase activity that is suggested to be responsible for hydrogen peroxide (H2O2) production. There also existed some malate dehydrogenase (EC 1.1.1.37) activity in the apoplast of suspension culture cells (in ionically and covalently bound cell wall protein fractions), possibly for the regeneration of NADH that is needed for peroxidase-catalysed H2O2 production. However, there is no proof of the existence of NADH in the apoplast. Nutrient medium peroxidases could be classified into acidic, slightly basic and highly basic isoenzyme groups by isoelectric focusing. Only acidic peroxidases were found in the covalently bound cell wall protein fraction. Several peroxidase isoenzymes across the whole pI range were detected in the protein fraction ionically bound to cell walls and in the soluble cellular protein fraction. One laccase-like isoenzyme with pI of approximately 8.5 was found in the nutrient medium that was able to form dehydrogenation polymer from coniferyl alcohol in the absence of H2O2. The total activity of this oxidase towards coniferyl alcohol was, however, several orders of magnitude smaller than that of peroxidases in vitro. According to 2D 1H-13C correlation NMR spectra, most of the abundant structural units of native lignin and released suspension culture lignin are present in the oxidase produced dehydrogenation polymer but in somewhat different amounts compared to peroxidase derived synthetic lignin preparations. A coniferin beta-glucosidase (EC 3.2.1.21) was observed to be secreted into the culture medium.
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PMID:Lignification related enzymes in Picea abies suspension cultures. 1206 Feb 56

In the present research we studied the photosynthetic traits and protective mechanisms against oxidative stress in two maize (Zea mays L.) genotypes differing in chilling sensitivity (Z7, tolerant and Penjalinan, sensitive) subjected to 5 degrees C for 5 days, with or without pretreatment by drought. The drought pretreatment decreased the symptoms of chilling injury in Penjalinan plants estimated as necrotic leaf area and maximum quantum yield of photosystem II. Furthermore, drought pretreatment diminished the level of lipid peroxidation caused by chilling in Penjalinan plants. After one day of recovery from chilling the Z7 and drought-pretreated Penjalinan plants showed higher net photosynthesis rates than the non-drought-pretreated Penjalinan plants, thereby decreasing the probability of generating reactive oxygen species. The greater net photosynthesis was correlated with the greater NADP-malate dehydrogenase activity. No differences in either the de-epoxidation state of the xanthophyll cycle or the antioxidant enzyme activities were found among the chilled groups of plants. However, a drastic decrease in ascorbate content was observed in chilled Penjalinan plants without drought pretreatment. As we found an increase of H2O2 content after drought pretreatment, we suggest its involvement as a signal in the drought-enhanced chilling tolerance of maize.
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PMID:Drought enhances maize chilling tolerance. II. Photosynthetic traits and protective mechanisms against oxidative stress. 1267 44

Experimental ishemia of rat myocardium was accompanied by increase of light sum (S) and maximal intensity (Imax) of chemiluminescence, amount of a malonic dialdehyde and conjugated dienes in cytoplasmic fraction. The activity of NADP-dependent malate dehydrogenase (EC 1.1.1.82; NADP-MDH) was 1.6 times higher in rat heart under ischemia. NADP-MDH was purified from normal and ischemia-exposed rat myocardium. Using NADP-MDH purified enzyme preparations the values of Hill coefficient for oxaloacetate (1.83 +/- 0.07 and 1.50 +/- 0.10) and Km for NADPH (0.058 +/- 0.003 and 0.096 +/- 0.004 mM) were determined for the enzyme at norm and under ischemia respectively. Effects of Fe2+, Ca2+, Cu2+ ions, H2O2, oxidized and reduced glutathione, adenine nucleotides influence on functioning of NADP-MDH from rat heart at norm and under ischemic conditions have been investigated.
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PMID:[Free-radical oxidation and regulation of cytoplasmic NADP-dependent malate dehydrogenase in rat cardiomyocytes at norm and under ischemia]. 1610 94

Oxidative damage to mitochondria caused by reactive oxygen species (ROS) has been implicated in the process of senescence as well as a number of senescence-related disorders in a variety of organisms. Whereas mitochondrial DNA was shown to be oxidatively modified during cellular senescence, mitochondrial protein oxidation is not well-understood. With the use of high-resolution, two-dimensional gel electrophoresis coupled with immunoblotting, we show here that protein carbonylation, a widely used marker of protein oxidation, increased in mitochondria during the senescence of peach fruit. Specific mitochondrial proteins including outer membrane transporter (voltage-dependent anion-selective channel, VDAC), tricarboxylic acid cycle enzymes (malate dehydrogenase and aconitase), and antioxidant proteins (manganese superoxide dismutase, MnSOD) were found as the targets. The oxidative modification was concomitant with a change of VDAC function and loss of catalytic activity of malate dehydrogenase and MnSOD, which in turn facilitated the release of superoxide radicals in mitochondria. Reduction of ROS content by lowering the environmental temperature prevented the accumulation of protein carbonylation in mitochondria and retarded fruit senescence, whereas treatment of fruit with H2O2 had the opposite effect. Our data suggest that oxidative damage of specific mitochondrial proteins may be responsible for impairment of mitochondrial function, thus, leading to fruit senescence. Proteomics analysis of mitochondrial redox proteins provides considerable information on the molecular mechanisms involved in the progression of fruit senescence.
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PMID:Oxidative damage of mitochondrial proteins contributes to fruit senescence: a redox proteomics analysis. 1923 64


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