Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Quantitative cytochemical techniques have been employed in a study of some of the acute effects of low doses (0.01----1 mU/liter) of TSH on the metabolism of guinea pig thyroid segments maintained in nonproliferative organ culture. The enzymes involved in the synthesis of NADP+ (NAD+ kinase), its reduction by the pentose-shunt (glucose 6-phosphate dehydrogenase), and its reoxidation both by the microsomal electron chain (diaphorase activity) and by participation in other cellular processes, have been examined. The effect of TSH on peroxidase activity has also been studied. After 10 min stimulation with TSH (1 mU/liter) there was a 60% increase in NAD+ kinase activity which preceded changes in the microsomal reoxidation of NADPH (up 33% by 30 min). There were no changes in the activity of glucose 6-phosphate dehydrogenase. There was a sustained rise in peroxidase activity which reached 129% over control after 30 min. This is the first in vitro demonstration of an acute stimulation of peroxidase and kinase activities by physiological concentrations of TSH. NADPH reoxidation after stimulation with TSH was such that the ratio of NADPH reoxidized via the microsomal respiratory pathway (diaphorase, hydrogen pathway 1) relative to that available for cytosolic utilization (hydrogen pathway 2) increased compared to the unstimulated controls. We suggest that increased NADP+ production (via NAD+ kinase activity) and the preferential shuttling of the NADPH for reoxidation via the microsomal respiratory pathway, coupled with greatly stimulated peroxidase activity, may be important regulators of the control of thyroglobulin iodination and hence thyroid hormone production.
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PMID:Acute stimulation of thyroidal NAD+ kinase, NADPH reoxidation, and peroxidase activities by physiological concentrations of thyroid stimulating hormone acting in vitro: a quantitative cytochemical study. 284 14

Nicotinamide adenine dinucleotide phosphate (NAD-PH) diaphorase histochemistry was used to localize cholinergic neurons in the pedunculopontine nucleus of neonatal and adult rats. Measurements of cell body areas revealed an average area around 200 microns2 at birth, followed by a significant increase to approximately 500 microns2 by 2 weeks of age. Thereafter, there was a decrease in cell area such that by 5 weeks of age the neurons had attained their adult size of around 300 microns2. The marked increase in cell size at the end of 2 weeks of age is discussed in relation to significant events in the development of locomotor and other rhythmic function control systems.
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PMID:Development of NADPH diaphorase-positive pedunculopontine nucleus neurons. 292 65

Based on cytochemical analysis, the enzyme NADP phosphatase is most concentrated in the so-called intercalary cisternae from the mid-region of the Golgi apparatus stack. Using free-flow electrophoresis to separate different Golgi regions of rat liver Golgi apparatus, the NADP phosphatase activity, based on estimation of the rate of release of inorganic phosphate from NADP under standard conditions, was similarly localized to membrane fractions from the center of electrophoretic separations. Peak specific activities for both a putative cis marker (NADH-cytochrome c reductase) and an established trans marker (galactosyltransferase) coincided with minima in NADP phosphatase activity, in agreement with the cytochemical observations. The pattern of distribution of enzyme activity for NADP phosphatase differed from that of both acid phosphatase and glucose-6-phosphatase. The pH optimum was 5.0, the Km for NADP was 0.6 mM and a corresponding production of NAD and inorganic phosphorus was shown. Taken together with other markers for free-flow electrophoresis separation, the NADP phosphatase will provide considerable utility as a specific marker to help identify intercalary cisternae of the mammalian Golgi apparatus and to monitor electrophoretic separations.
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PMID:NADP phosphatase as a marker in free-flow electrophoretic separations for cisternae of the Golgi apparatus midregion. 300 95

The nicotinamide nucleotide dimers (NAD)2 and (NADP)2, obtained by electrochemical reduction of NAD+ and NADP+, are able to reduce such single-electron acceptors as the proteins cytochrome c, azurin and methaemoglobin, though at different rates. Under the same conditions the reduced nicotinamide coenzymes NADH and NADPH are not able to reduce these proteins at measurable rates unless a catalyst (phenazine methosulphate or NADH-cytochrome c reductase in the case of cytochrome) is present. The redox mechanism seems to involve the formation of an NAD(P). radical that in the presence of O2 gives rise to superoxide (O2.-), since superoxide dismutase inhibited these reactions.
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PMID:Oxidation of nicotinamide coenzyme dimers by one-electron-accepting proteins. 302 35

Ferredoxin-NADP reductase from Euglena gracilis Klebs var. Bacillaris Cori purified to apparent homogeneity, yields a typical 36 kDa and an unusual 15 kDa polypeptide on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, exhibits a typical flavoprotein spectrum, contains FAD, and catalyzes NADPH-dependent iodonitrotetrazolium-violet diaphorase, NADPH-specific ferredoxin-dependent cytochrome-c-550 reductase and NADPH-NAD transhydrogenase activities. Rabbit antibody to the purified FNR blocks these activities specifically and also blocks the iodonitrotetrazolium-violet diaphorase activity of Euglena chloroplast completely. The low iodonitrotetrazolium-violet diaphorase activity in the plastidless mutant, W10BSmL, is mitochondrial and is not specifically blocked by the ferredoxin-NADP reductase antibody. Dark-grown non-dividing (resting) wild-type Euglena cells show a 4-fold increase in ferredoxin-NADP reductase activity during greening at 970 lx. Half of the low ferredoxin-NADP reductase activity in dark-grown cells is initially soluble, but by the end of chloroplast development nearly all of the enzyme is membrane-bound. The binding of ferredoxin-NADP reductase on exposure to light correlates with the extent of thylakoid membrane formation. Immunoblots of wild-type extracts during greening indicate that the 15 kDa polypeptide increases in the same manner as the extent of reductase binding to thylakoid membranes.
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PMID:Purification, properties, and cellular localization of Euglena ferredoxin-NADP reductase. 312 Jul 72

Nicotinamide adenine dinucleotide phosphate diaphorase reactive neurons were found in several regions of human brainstem. Three major groups were located in the medulla: a dorsomedial group in the central gray and floor of the fourth ventricle, a ventromedial group in the vicinity of the medullary raphe, and a lateral group in the lateral reticular nucleus. In the upper pons a large cluster of reactive neurons was centered in the nucleus centralis oralis extending into the locus coeruleus and dorsal tegmental region. A second cluster in the lateral parabrachial nucleus merged with this group more rostrally and continued into the midbrain tegmentum (paracoeruleus-cuneiform group). Nicotinamide adenine dinucleotide phosphate diaphorase neurons in this region often contained acetylcholinesterase activity. A second midbrain group was seen in the nucleus paranigralis. Aside from these discrete neuronal collections, scattered reactive neurons were found in the medullary reticular formation, periaqueductal gray, inferior colliculus and superior colliculus. Nicotinamide adenine dinucleotide phosphate diaphorase neurons were classified into three groups based on somal size. Parvocellular neurons (10-20 micron) were primarily found in the ventromedial medulla and lateral parabrachial nucleus. Intermediate neurons (20-25 micron) were located in the paranigralis nucleus and dorsomedial medulla. Magnocellular neurons (25-35 micron) were characteristically found in the lateral reticular nucleus and paracoeruleus-cuneiform region. Nicotinamide adenine dinucleotide phosphate diaphorase reactive neurons are present in substantial numbers in human brainstem and their distribution is complex. They represent the caudal end of a widespread network of nicotinamide adenine dinucleotide phosphate diaphorase-enriched neurons that extend rostrally from the brainstem reticular formation into the basal forebrain, striatum, and cerebral cortex.
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PMID:Morphology and distribution of nicotinamide adenine dinucleotide phosphate (reduced form) diaphorase reactive neurons in human brainstem. 317 92

1. Measurements were made of the activities of the following enzymes of glycerolipid synthesis in homogenates of interscapsular brown adipose tissue obtained from rats subjected to a 4 degrees C environment for time periods of 6 h up to 12 days: fatty acyl-CoA synthetase (FAS), mitochondrial and microsomal forms of glycerolphosphate acyltransferase (GPAT), monoacylglycerolphosphate acyltransferase (MGPAT) and Mg2+-dependent phosphatidate phosphohydrolase (PPH). 2. Relative to tissue DNA content, the activities of mitochondrial GPAT, MGPAT and Mg2+-dependent PPH were significantly increased after 1 day of exposure to cold, and continued to increase thereafter. By contrast, FAS and microsomal GPAT activities were unchanged relative to tissue DNA. 3. The time profile of the increase in MGPAT activity correlated well with a concomitant increase in the microsomal marker NADP+-cytochrome c reductase. Changes in mitochondrial GPAT and in Mg2+-dependent PPH activities were larger in amplitude than that of MGPAT. 4. It is proposed that these selective changes in enzyme activity may be associated with the onset of brown-adipose-tissue hyperplasia or possibly with an increase in triacylglycerol synthesis during cold-acclimation.
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PMID:Changes in activities of some enzymes of glycerolipid synthesis in brown adipose tissue of cold-acclimated rats. 317 17

The yeast Candida parapsilosis possesses two routes of electron transfer from exogenous NAD(P)H to oxygen. Electrons are transferred either to the classical cytochrome pathway at the level of ubiquinone through an NAD(P)H dehydrogenase, or to an alternative pathway at the level of cytochrome c through another NAD(P)H dehydrogenase which is insensitive to antimycin A. Analyses of mitoplasts obtained by digitonin/osmotic shock treatment of mitochondria purified on a sucrose gradient indicated that the NADH and NADPH dehydrogenases serving the alternative route were located on the mitochondrial inner membrane. The dehydrogenases could be differentiated by their pH optima and their sensitivity to amytal, butanedione and mersalyl. No transhydrogenase activity occurred between the dehydrogenases, although NADH oxidation was inhibited by NADP+ and butanedione. Studies of the effect of NADP+ on NADH oxidation showed that the NADH:ubiquinone oxidoreductase had Michaelis-Menten kinetics and was inhibited by NADP+, whereas the alternative NADH dehydrogenase had allosteric properties (NADH is a negative effector and is displaced from its regulatory site by NAD+ or NADP+).
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PMID:The alternative respiratory pathway of the yeast Candida parapsilosis: oxidation of exogenous NAD(P)H. 326 91

Yeast glutathione reductase exists in a single molecular form which exhibits preferred NADPH and weak NADH linked multifunctional activities. Kinetic parameters for the NADPH and NADH linked reductase, transhydrogenase, electron transferase and diaphorase reactions have been determined. The functional preference for the NADPH linked reductase reaction is kinetically related to the high catalytic efficiency and low dissociation constants for substrates. NADP+ and NAD+ may interact with two different sites or different kinetic forms of the enzyme. The active site disulfide and histidine are required for the reductase activity but are not essential to the transhydrogenase, electron transferase and diaphorase activities. Amidation of carboxyl groups and Co(II) chelation of glutathione reductase facilitate the electron transferase reaction presumably by encouraging the formation of an anionic flavosemiquinone.
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PMID:Multifunctional activities of yeast glutathione reductase. 329 44

A method is described for increasing the response of enzyme immunoassays employing alkaline phosphatase as the label initiating 2 sequential catalytic reactions. First, NADP is dephosphorylated to produce NAD, which catalytically activates a specific redox-cycle involving the enzymes alcohol dehydrogenase and diaphorase. During each turn of the cycle 1 molecule of a tetrazolium salt is reduced to an intensely coloured formazan. The method is capable of detecting as little as 0.01 amol alkaline phosphatase, and when applied to an immunoassay for TSH a sensitivity (zero + 2.5 standard deviations) of 0.0013 mIU/l was obtained.
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PMID:Enzyme amplification for immunoassays. Detection limit of one hundredth of an attomole. 351 23


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