Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.99.3 (diaphorase)
 5,903 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pea leaf mitochondria showed complex kinetics for malate metabolism. O2 uptake increased as malate concentration increased from 0 to 10 mM, reached a plateau between 10 and 20 mM malate, and then increased again up to 40 mM malate. Analysis of the products of malate oxidation by high-performance liquid chromatography revealed that the first phase of O2 uptake coincided with the synthesis of both pyruvate and oxalacetate (OAA) while the second phase of O2 uptake at higher malate levels usually occurred with a large increase in OAA formation. The biphasic response in O2 uptake and the changing ratios of pyruvate and OAA synthesis did not appear to be the direct result of the differing Km values of malate dehydrogenase and malic enzyme. Rather, they resulted from thermodynamic properties of these two malate oxidases and the kinetics of the two NADH dehydrogenases found in plant mitochondria. At low malate concentrations the rotenone-sensitive NADH dehydrogenase was active and could accept electrons from both malate oxidases. This NADH dehydrogenase became saturated at about 10 mM malate. At higher malate concentrations the rotenone-insensitive NADH dehydrogenase was increasingly important and its increased electron transport capacity was best exploited by malate dehydrogenase. At the higher malate concentrations an increasing portion of the electrons from malate reduce O2 through the alternative oxidase. Although this coincided with the second phase of malate-dependent O2 uptake it was not required for this phase to be seen.
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PMID:Changes in the electron transport chain of pea leaf mitochondria metabolizing malate. 662 11

The activity of NAD-linked alpha-glycerol-3-phosphate dehydrogenase (NAD-G3PDH; EC 1.1.1.8) was depressed by 35% when the thyroid hormone 3,3',5-triiodo-L-thyronine (20 micrograms/liter) was added to the serum-free, hormonally supplemented medium of cultured neonatal rat heart cells. The degree of depression was greater (65%) when the medium contained normal serum levels of hydrocortisone and insulin. There is a dramatic inverse dose-response relationship between triiodothyronine levels and NAD-G3PDH activity. The classic elevation by thyroid hormones of the FAD-linked alpha-glycerol-3-phosphate dehydrogenase (FAD-G3PD; EC 1.1.99.5) was observed concurrently. The medium-glucose depletion rate in triiodothyronine-free cells was depressed 32% through 11 days-in-culture, indicating reduced glycolytic activity. The activities of nine other metabolically important enzymes which were measured during this study, including hexokinase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphofructokinase, pyruvate kinase, malate dehydrogenase, NAD-isocitrate dehydrogenase, NADH cytochrome c reductase, and succinic cytochrome c reductase, did not respond to varying triiodothyronine concentrations.
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PMID:Triiodothyronine depresses the NAD-linked glycerol-3-phosphate dehydrogenase activity of cultured neonatal rat heart cells. 669 42

A serum-free, hormone-supplemented medium (SFHM) for maintaining neonatal rat heart cells in culture has been developed in this laboratory (Mohamed et al., 1983). Morphological assessment of heart cells grown in SFHM show it to be similar to commonly used serum-supplemented media. To quantitatively compare cell behavior in SFHM with serum-supplemented media, the activities of ten regulatory enzymes which represent four metabolic pathways were studied in heart cells cultured in SFHM. The enzyme activities which were measured included hexokinase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphofructokinase, pyruvate kinase, NAD+-linked sn-glycerol-3-phosphate dehydrogenase, malate dehydrogenase, NAD+-linked isocitrate dehydrogenase, NADH-cytochrome c reductase, and succinic cytochrome c reductase. Rat heart cells maintained in culture on SFHM are not only qualitatively and quantitatively similar to those maintained in serum-supplemented medium but also provide a more suitable model system for metabolic studies of neonatal cardiac tissue for several reasons: 1) many enzyme activities that may represent dedifferentiation are elevated by serum; 2) NAD-linked glycerol-3-phosphate dehydrogenase activity in cells maintained on SFHM is similar to the in vivo activity; 3) cells beat at or near the in vivo frequency and can be maintained 3 months on SFHM; 4) the SFHM is chemically defined and thus can be completely manipulated by the investigator. The effects of three concentrations of hydrocortisone (HC) (5,000 ng/ml, 50 micrograms/ml, 0 ng/ml) on heart cells cultured in SFHM supported our previous conclusion that function (beating) and growth (protein accumulation) are inversely related in cultured neonatal rat heart cells.
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PMID:Control of enzyme activity levels by serum and hydrocortisone in neonatal rat heart cells cultured in serum-free medium. 674 46

Exogenous NAD+ stimulated the rotenone-resistant oxidation of all the NAD+-linked tricarboxylic acid-cycle substrates in mitochondria from Jerusalem artichoke (Helianthus tuberosus L.) tubers. The stimulation was not removed by the addition of EGTA, which is known to inhibit the oxidation of exogenous NADH. It is therefore concluded that added NAD+ gains access to the matrix space and stimulates oxidation by the rotenone-resistant NADH dehydrogenase located on the matrix surface of the inner membrane. Added NAD+ stimulated the activity of malic enzyme and displaced the equilibrium of malate dehydrogenase; both observations are consistent with entry of NAD+ into the matrix space. Analysis of products of malate oxidation showed that rotenone-resistant oxygen uptake only occurred when the concentration of oxaloacetate was low and that of NADH was high. Thus it is proposed that the concentration of NADH regulates the activity of the two internal NADH dehydrogenases. Evidence is presented to suggest that the rotenone-resistant NADH dehydrogenase is engaged under conditions of high phosphorylation potential, which restricts electron flux through the rotenone-sensitive dehydrogenase (coupled to ATP synthesis).
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PMID:Regulation of malate oxidation in plant mitochondria. Response to rotenone and exogenous NAD+. 681 64

Membrane-bound antigens of the respiratory chain of Micrococcus luteus were analyzed by crossed immunoelectrophoresis after growth of the organism in the presence of 59Fe, the flavin adenine dinucleotide-flavin mononucleotide precursor D-[2-14C]riboflavin, or the heme precursor 5-amino-[4-(14)C]levulinic acid. Using zymograms and procedures of selective extraction in conjunction with autoradiography, it was possible to resolve and partially characterize a number of antigens. Succinate dehydrogenase (EC 1.3.99.1) was shown to possess covalently bound flavin and nonheme iron and was possibly present as a complex with cytochrome. Three other dehydrogenases, namely, NADH dehydrogenase, NAD(P)H dehydrogenase (EC 1.6.99.3), and malate dehydrogenase (EC 1.1.1.37), contained flavin in noncovalent linkage, the NAD(P)H dehydrogenase also possessing nonheme iron. Four other discrete antigens (or antigen complexes) containing both iron and heme centers also resolved, as were two minor immunogens possessing iron as the sole detectable prosthetic group.
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PMID:Immunochemical analysis of respiratory-chain components of micrococcus luteus (lysodeikticus). 684 87

The maximal rate of some cerebral enzymatic activities related to energy transduction (hexokinase; phosphofructokinase; lactate dehydrogenase; citrate synthase; malate dehydrogenase; total NADH-cytochrome c reductase; cytochrome oxidase), amino acid metabolism (glutamate decarboxylase; glutamate dehydrogenase) and cholinergic metabolism (acetylcholine esterase) were tested in the cerebral cortex and in sub-cortical area of rats. The evaluations were performed both in the homogenate in toto and in the crude mitochondrial fraction, before and after a postdecapitative normothermic ischemia of 5, 10, 20, and 40 min duration. The results are discussed also with respect to the pharmacological pretreatment with two biological substances which may modulate amino acid (L-alanine) and phospholipid metabolism (CDP-choline). The analysis of the present data suggests the occurrence in brain tissue of a variety of interrelated factors implicated in the ischemia-induced changes of the maximal rate of the enzymatic activities related to the energy transduction. These include: (a) rearrangement of the enzymatic activities because of the changed metabolic and chemico-physical condition; (b) decrease in the activity of enzymes related to the electron transfer chain and glycolysis; (c) changes in enzymes related to mitochondrial membranes. The effects of in vivo administration of alanine or CDP-choline, even if significant, are not consistent throughout the time period studied.
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PMID:Changes induced by ischemia on some cerebral enzymatic activities related to energy transduction and amino acid metabolism. 685 30

The article deals with the results of histochemical study of some redox and proteolytic enzymes (SDH, MDH, NAD-diaphorase, LDH, and acid and alkaline phosphatase) in experiments on animals in various periods after infliction of a craniocerebral injury and on autopsy material, i.e. the brain of patients who had died from severe craniocerebral injury incompatible with life. It is shown that the activity of all enzymes decreases (SDH, MDH, NAD-diaphorase, and alkaline phosphatase) or increases (LDH, acid phosphatase) in various periods after the injury. The results were compared with the findings of morphological examination of the same brain areas performed by means of neurohistological methods.
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PMID:[Redox and proteolytic enzymes in brain tissue after a concussion]. 689 60

Histochemical studies have been made of the isocitrate dehydrogenase, succinic dehydrogenase, malate dehydrogenase, glutamate dehydrogenase, DPN diaphorase, TPN diaphorase, delta 5-3 beta-hydroxysteroid dehydrogenase and monoamine oxidase in the caput, corpus and cauda epididymides of normal and alpha chlorohydrin (6.5 mg/kg/9 days) treated rats. Administration of alpha chlorohydrin in a low dose caused a conspicuous decrease in all these enzymes except delta 5-3 beta-HSD, in various cell types of epididymal epithelium and sperms. Biochemical estimations of isocitrate dehydrogenase, succinic dehydrogenase, malate dehydrogenase and delta 5-3 beta-HSD have further supported and confirmed these histochemical observations. These changes in enzyme activities after treatment with low dose of alpha chlorohydrin strongly suggest that TCA cycle and amino acid metabolism of epididymis become defective, much earlier before any histological damage to the epididymis becomes visible.
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PMID:Effects of low doses of alpha chlorohydrin on the dehydrogenases and oxidases of rat epididymal epithelium and sperms: a correlative histochemical and biochemical study. 694 44

Treatment of M. lysodeikticus protoplasts with subtilisin or pronase did not affect their permeability and led to a digestion of 20--30% of protein. DS-Na electrophoresis of protoplast membranes resulted in disappearance of three protein bands. This suggests that the outer surface of M. lysodeikticus protoplasts contains three proteins other than respiratory chain enzymes, which are subjected to an attack by proteinases. Treatment of the M. lysodeikticus membranes, isolated by osmotic shock, with proteinases resulted in a digestion of 20--50% of protein. The factors preventing the interaction between the membrane components (e.g. decrease of Mg2+ concentration, ultrasound, KCl, EDTA and particularly detergents) favoured the proteolysis; however, the bulk of the proteins remained insensitive to the effect of proteinases. The membranes pretreated with DS-Na or chlorophorm--methanol mixture proved to be good substrates for proteinases. Treatment of the membrane fraction with proteolytic enzymes allowed to obtain some data on localization of respiratory chain enzymes in the membrane stroma of M. lysodeikticus. Thus, cytochrome c is localized nearer to the membrane surface than cytochromes a and b, while malate dehydrogenase is plunged deeper into the membrane stroma as compared to NADH dehydrogenase.
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PMID:[Proteolysis as an approach to the study of protein distribution in the membrane of Micrococcus lysodeikticus]. 699 76

The energy metabolism of the English E-CMO strain of contagious equine metritis bacterium was studied in whole cells and cell extracts. This bacterium appears to have an active Krebs cycle and probably obtains energy by oxidative phosphorylation since glycolysis and the hexose monophosphate pathways appear to be absent. These conclusions are based on the findings that [U-14C]glucose incorporation by this bacterium is below the level of detection, and that respiration is stimulated by Krebs cycle intermediates (i.e., malate, citrate, and succinate), but not by glucose, fructose, maltose, or sucrose. Furthermore, support comes from the fact that enzymes generally associated with the Krebs cycle and electron transport (i.e., malate dehydrogenase, succinate dehydrogenase, isocitrate dehydrogenase, fumarate hydratase, malate dehydrogenase [decarboxylating], cytochrome oxidase, superoxide dismutase, NADH dehydrogenase, and catalase) were detected. Those enzymes normally associated with glycolysis and the hexose monophosphate pathways (i.e., hexokinase, glucose 6-phosphate dehydrogenase, fructose biphosphate aldolase, glycerol 3-phosphate dehydrogenase, phosphoenolpyruvate carboxykinase, pyruvate kinase, phosphate acetyl transferase, acetate kinase, alcohol dehydrogenase, and lactate dehydrogenase) were below the level of detection.
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PMID:Energy metabolism of the contagious equine metritis bacterium. 708 71


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