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)

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

Changes in the activity of 13 enzymes are described in the process of cytodifferentiation of the nerve cells of spinal ganglion, the motor neurons of spinal cord and large nerve cells of the III layer of tectum opticum in 7, 10 and 21 day old chick embryos. Cytophotometry was performed with MZFV-1 (LOMO) by means of plug-method. A relatively high activity of glucose-6-phosphat dehydrogenase, diaphorase, alpha-glycerophosphate dehydrogenase and, partially, acetylcholine esterase was found already in the 7 days old embryo. The activity of monoamine oxidase, aldolase-glyceroaldehyde phosphate dehydrogenase, isocitrate dehydrogenase, glutamate dehydrogenase increased markedly on the 21st day. When studying the reciprocal distribution of two enzymes in separate cells, pairs of enzymes with a high value of correlation coefficient were found. The cytodifferentiation was found to be accompanied by changes in the coefficient of correlation of the same pair of enzymes.
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PMID:[Enzymes in the process of neuronal differentiation of the hen spinal ganglion, spinal cord and tectum opticum. A cytophotometric histochemical study]. 683 47

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

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

Rapidly sedimenting endoplasmic reticulum (RSER), which is known to be a complex between endoplasmic reticulum and mitochondria, was isolated from rat liver and purified through a sucrose density gradient by centrifugation according to a well established procedure previously published by G. C. Shore and J. R. Tata. This complex was characterized by microsomal (NADPH-cytochrome c reductase) and mitochondrial (succinate-cytochrome c reductase and NADP-isocitrate dehydrogenase) marker enzymes and was examined for the ability to synthesize microsomal lipids and mitochondrial polyglycerophosphatides. Results of these experiments showed that the RSER is capable of synthesizing key microsomal lipids, i.e., phosphatidic acid, phosphatidylcholine, and neutral lipids, as well as mitochondrial phosphatidylglycerosphate and phosphatidic acid, phosphatidylcholine, and neutral lipids, as well as mitochondrial phosphatidylglycerophosphate and phosphatidylglycerol. Furthermore, the level of synthesis of these lipids paralleled the level of activity of microsomal and mitochondrial marker enzymes found in the RSER preparation. Details of these experimental findings and some implications are discussed in view of the possible functional role of RSER.
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PMID:Biosynthesis of microsomal phospholipids and mitochondrial polyglycerophosphatides in rapidly sedimenting endoplasmic reticulum. 717 97

Oxidative stress is associated with the formation of oxidized glutathione (GSSG) in the cells, which can form mixed disulfide with proteins leading to alteration of their function. The present study looks at the effect of in vitro exposure of GSSG on intestinal mitochondria and brush border membrane (BBM). Incubation with 1 mM GSSG increased the protein bound GSH in mitochondria by 15-fold. This was associated with loss of activity of certain mitochondrial enzymes such as succinic dehydrogenase, isocitrate dehydrogenase, total ATPase and NADH dehydrogenase whereas NADH oxidase was not affected. A similar treatment of BBMV with GSSG increased the protein bound GSH by 4.7-fold without altering its enzyme activity. Exposure to GSSG had no effect on the Na(+)-dependent glucose transport by BBMV. These studies suggest that GSSG formed during oxidative stress may modify thiol groups in proteins by forming mixed disulfides leading to functional alteration of certain cellular proteins.
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PMID:Effect of oxidized glutathione on intestinal mitochondria and brush border membrane. 767 Nov 37

Aurintricarboxylic acid (ATA), an inhibitor of Ca(2+)-dependent endonuclease activity, is often used to implicate a role for increased intracellular calcium in mechanistic toxicology studies. We report here on the ability of ATA to inhibit the activity of several NAD(H)/NADP(H)-requiring enzymes (purified or cellular homogenates), including lactic dehydrogenase, alcohol dehydrogenase, cytochrome c reductase, ethoxycoumarin o-dealkylase, isocitric dehydrogenase, glutathione reductase and glucose-6-phosphate dehydrogenase. These results were compared with the ability of ATA to inhibit micrococcal nuclease and rat liver Ca(2+)-dependent endonuclease activity in similar incubations. With the exception of alcohol dehydrogenase, ATA was a potent inhibitor of each of the purified enzymes, with IC50s ranging from 0.5 to 82 microM. In cell homogenates, however, ATA was from 10 to 100-fold less potent at inhibiting these enzymes. When exogenous protein was added to purified enzyme incubations, the effect of ATA was similarly diminished. Our results demonstrate that ATA inhibits a wide range of NAD(H)/NADP(H)-requiring enzymes in in vitro incubations using purified enzymes, but that the inhibitory effects are markedly reduced in incubations which more closely resemble a cellular milieu.
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PMID:Inhibition of NAD(H)/NADP(H)--requiring enzymes by aurintricarboxylic acid. 855 68

Mitochondria isolated from rabbit soleus (98% type I) and gracilis (99% type IIb) skeletal muscle were compared for compositional differences. Whole muscle mitochondrial contents were 14.5 +/- 1.2 mg/g of wet weight in soleus and 5.3 +/- 0.6 mg/g in the gracilis muscle, a 2.7-fold difference. Maximal pyruvate plus malate oxidase activity in gracilis mitochondria was roughly 75% of that in soleus mitochondria. In contrast, glycerol 3-phosphate (G-3-P) oxidation was 10-fold greater in gracilis mitochondria. Both soleus and gracilis mitochondria exhibited additive pyruvate and G-3-P oxidase activities. In general, citric acid cycle enzyme activities were higher in soleus mitochondria. A notable exception was isocitrate dehydrogenase, which was twofold higher in gracilis mitochondria. Substrate cytochrome c reductase activities indicated that the electron transport chain (ETC) of soleus mitochondria possess roughly twice the capacity for both NADH and succinate oxidation. Similarly, the maximal activities of NADH dehydrogenase and succinate dehydrogenase were roughly twofold higher in soleus mitochondria. The findings demonstrate that mitochondria isolated from types I and IIb skeletal muscle differ substantially in composition. Furthermore, the relatively similar pyruvate plus malate oxidase activities in the face of markedly different ETC capacities suggest that the interaction between matrix dehydrogenases and the ETC may differ in mitochondria isolated from types I and IIb skeletal muscle.
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PMID:Characteristics of mitochondria isolated from type I and type IIb skeletal muscle. 877 34

Mitochondrial biogenesis was studied during differentiation of two immortalized cell lines (C2C12, 3T3) with enzyme measurements, Northern blots, and quantitative ultrastructure. Citrate synthase, isocitrate dehydrogenase, and 3-hydroxyacyl-CoA dehydrogenase (nuclear encoded, mitochondrial matrix location) showed linear, four- to sixfold increases in enzymatic activity in C2C12 cells but increased exponentially in 3T3 cells. Cytochrome oxidase and NADH dehydrogenase (nuclear and mitochondrial encoded, cristae location) increased to a lesser extent and with a pattern dissimilar to the first group. Northern blots and activity of succinate dehydrogenase (cristae location but entirely nuclear encoded) suggested the groupings were based on location of the genes rather than the mature enzyme. However, quantitative electron microscopy and comparisons with adult tissue suggested that mitochondrial ultrastructure can influence the change in cristae enzymes. Cristae surface area per unit mitochondrial volume and per unit cell volume increased much less than did cristae enzymes. Available space on the inner membrane may become limiting and account for some aspects of the pattern of change in electron transport enzymes during differentiation.
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PMID:Mitochondrial biogenesis during cellular differentiation. 914 61

The enzyme isocitrate dehydrogenase (IDH, EC 1.1.1.42) can exhibit activation by one of its products, NADPH. This activation is competitively inhibited by the substrate NADP+, whereas NADPH competes with NADP+ for the catalytic site. Experimental observations briefly presented here have shown that if IDH is coupled to another enzyme, diaphorase (EC 1.8.1.4), which transforms NADPH into NADP+, the system can attain either one of two stable states, corresponding to a low and a high NADPH concentration. The evolution toward either one of these stable states depends on the time of addition of diaphorase to the medium containing IDH and its substrate NADP+. We present a theoretical and numerical analysis of a model for the IDH-diaphorase bienzymatic system, based on the regulatory properties of IDH. The results confirm the occurrence of bistability for parameter values derived from the experiments. Depending on the total concentration of NADP+ plus NADPH and the concentration of IDH, the system can either admit a single steady state or display bistability. We obtain an expression for the critical time t*, before which diaphorase addition leads to the lower steady state and after which addition of the enzyme leads to the upper steady state of NADPH. The analysis is extended to the case where the second substrate of IDH, isocitrate, is consumed in the course of the reaction without being regenerated. Bistability occurs only as a transient phenomenon in these conditions.
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PMID:Bistability in the isocitrate dehydrogenase reaction: an experimentally based theoretical study. 951 21


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