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:1.6.99.1 (NADPH-diaphorase)
3,903 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

NADH was metabolized both by serum components and at the cell surface. The metabolism by serum was either oxidation to NAD+, or hydrolysis of the pyrophosphate to yield nicotinamide mononucleotide (reduced) (NMNH) and AMP. NMNH was further hydrolysed to yield nicotinamide riboside (reduced) (NRH), which was stable. NAD+ was hydrolysed (although at a slower rate than was NADH), but was also reduced to yield NADH. The reduction of NAD+ was catalysed by the enzyme serum L(+)lactate dehydrogenase (EC 1.1.1.27) and was dependent on the concentration of L(+)lactate in the serum. NADPH was hydrolysed in a similar manner to NADH but not oxidized by serum. NADH generated from NAD+ by serum derived from human, foetal calf and horse sources was capable of driving the bioreductive activation of CB 1954 by the enzyme DT diaphorase. Cell surfaces oxidized NADH to NAD+, but did not oxidize NADPH or NRH. These observations suggest that NAD(P)H would be unsuitable as a source of reducing equivalents for the bioreductive activation of prodrugs by a reductase enzyme in Antibody Directed Enzyme Prodrug Therapy (ADEPT). In contrast, NAD+ (which could act as a source of NADH) and NRH could avoid the shortcomings of NAD(P)H, and act as suitable cofactors for an enzyme in an ADEPT system.
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PMID:Metabolism of NAD(P)H by blood components. Relevance to bioreductively activated prodrugs in a targeted enzyme therapy system. 138 14

This paper describes the development of the rat vomeronasal organ from the stage of anlage until adulthood. Groups of four rats were sacrificed daily from prenatal day 13 (E13) until birth; at days 2, 4, 7, 10, 14 and 16 after birth; weekly from day P21 to P42 plus an additional group of adults. The vomeronasal organs were processed for light microscopy, including alcian blue-PAS and NADH-diaphorase reactions, and also for electron microscopy. For summarizing our results we propose the following developmental stages: 1. Anlage (E13). 2. Early morphogenesis (E14-16). 3. Late morphogenesis (E17 to birth). 4. Initiation of secretory activity (First postnatal week). 5. Cytoarchitectural maturity (2nd postnatal week). 6. Complete maturity (From 3rd postnatal week onwards). Our results on the maturation of the histological structure and the histochemical reactions, indicate that there may be some functional activity at birth but the development of the organ still continues during the first three postnatal weeks to acquire its full functional capability.
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PMID:Developmental stages of the vomeronasal organ in the rat: a light and electron microscopic study. 144 18

The toxicity of CB 1954 [5-(aziridin-1-yl)-2,4-dinitrobenzamide] towards human cells was greatly enhanced by NADH (when foetal calf serum was present in the culture medium) and by nicotinamide riboside (reduced) (NRH), but not by nicotinate riboside (reduced). Co-treatment of human cells with CB 1954 and NADH resulted in the formation of crosslinks in their DNA. The toxicity produced by other DNA crosslinking agents was unaffected by reduced nicotinamide compounds. When caffeine was included in the medium, a reduction in the cytotoxicity of CB 1954 occurred. The toxicity experienced by human cell lines after exposure to CB 1954 and NADH was proportional to their levels of the enzyme DT diaphorase NAD(P)H dehydrogenase (quinone), EC 1.6.99.2. It is concluded that NRH, which we have shown to be a co-factor for rat DT diaphorase (Friedlos et al., Biochem Pharmacol 44: 25-31, 1992), is generated from NADH by enzymes in foetal calf serum, and stimulates the activity of human DT diaphorase towards CB 1954.
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PMID:Potentiation of CB 1954 cytotoxicity by reduced pyridine nucleotides in human tumour cells by stimulation of DT diaphorase activity. 144 31

A nitroreductase enzyme has been isolated from Escherichia coli B. This enzyme is an FMN-containing flavoprotein with a molecular mass of 24 kDa and requires either NADH or NADPH as a cofactor. Partial protein sequence analysis showed extensive homology with the "classical nitroreductase" of Salmonella typhimurium and a nitroreductase induced in Enterobacter cloacae. In common with the Salmonella enzyme, the E. coli B enzyme is capable of reducing nitrofurazone. The E. coli nitroreductase is also capable of reducing the anti-tumour agent CB1954 [5-(aziridin-1-yl)-2,4-dinitrobenzamide], a property shared with the mammalian enzyme DT diaphorase [NAD(P)H dehydrogenase (quinone)] as isolated from Walker cells. The reduction of CB1954 by the E. coli enzyme results in the generation of cytotoxic species. Both enzymes also share the properties of being able to reduce quinones and are both inhibited by dicoumarol. The nitroreductase is a more active enzyme against CB1954 (kcat = 360 min-1) than Walker DT diaphorase (kcat = 4 min-1) and also has a lower Km for NADH (6 vs 75 microM).
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PMID:The bioactivation of 5-(aziridin-1-yl)-2,4-dinitrobenzamide (CB1954)--I. Purification and properties of a nitroreductase enzyme from Escherichia coli--a potential enzyme for antibody-directed enzyme prodrug therapy (ADEPT). 147 94

The chemoarchitecture of the pretectal complex of the rabbit was examined in sections stained by acetylcholinesterase (AChE) and reduced nicotinamide adenine dinucleotide (NADH) diaphorase in the coronal, horizontal and sagittal plane. Twelve different subdivisions can be identified in the rabbit pretectum on the basis of the distribution of both histochemical markers. According to the standard terminology, the pretectal complex of the rabbit consists of: the nucleus of the optic tract; the anterior, posterior, olivary and medial pretectal nuclei; the nucleus of the posterior commissure; the periventricular subcommissural gray; the suprageniculate and internal suprageniculate nuclei, and the dorsal, lateral and medial terminal nuclei of the accessory optic system. The combined use of several sectioning planes and the histochemical mapping of AChE and NADH diaphorase have been of value in resolving the structural limits within transitional regions of the pretectum.
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PMID:The pretectal complex of the rabbit: distribution of acetylcholinesterase and reduced nicotinamide adenine dinucleotide diaphorase activities. 151 63

Xanthine dehydrogenase (XDH) from the unicellular green alga Chlamydomonas reinhardtii has been purified to electrophoretic homogeneity by a procedure which includes several conventional steps (gel filtration, anion exchange chromatography and preparative gel electrophoresis). The purified protein exhibited a specific activity of 5.7 units/mg protein (turnover number = 1.9 .10(3) min-1) and a remarkable instability at room temperature. Spectral properties were identical to those reported for other xanthine-oxidizing enzymes with absorption maxima in the 420-450 nm region and a shoulder at 556 nm characteristic of molybdoflavoproteins containing iron-sulfur centers. Chlamydomonas XDH was irreversibly inactivated upon incubation of enzyme with its physiological electron donors xanthine and hypoxanthine, in the absence of NAD+, its physiological electron acceptor. As deduced from spectral changes in the 400-500 nm region, xanthine addition provoked enzyme reduction which was followed by inactivation. This irreversible inactivation also took place either under anaerobic conditions or whenever oxygen or any of its derivatives were excluded. Adenine, 8-azaxanthine and acetaldehyde which could act as reducing substrates of XDH were also able to inactivate it upon incubation. The same inactivating effect was observed with NADH and NADPH, electron donors for the diaphorase activity associated with xanthine dehydrogenase. In addition, partial activities of XDH were differently affected by xanthine incubation. We conclude that xanthine dehydrogenase inactivation by substrate is due to an irreversible process affecting mainly molybdenum center and that sequential and uninterrupted electron flow from xanthine to NAD+ is essential to maintain the enzyme in its active form.
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PMID:Purification and substrate inactivation of xanthine dehydrogenase from Chlamydomonas reinhardtii. 152 76

The reductant dependence of iron mobilization from isolated rabbit reticulocyte endosomes containing diferric transferrin is reported. The kinetic effects of acidification by a H(+)-ATPase are eliminated by incubating the endosomes at pH 6.0 in the presence of 15 microM FCCP to acidify the intravesicular milieu and to dissociate 59Fe(III) from transferrin. In the absence of reductants, iron is not released from the vesicles, and iron leakage is negligible. The second-order dependence of rate constants and amounts of 59Fe mobilized from endosomes using ascorbate, ferrocyanide, or NADH are consistent with reversible mechanisms. The estimated apparent first-order rate constant for mobilization by ascorbate is (2.7 +/- 0.4) x 10(-3) s-1 in contrast to (3.2 +/- 0.1) x 10(-4) s-1 for NADH and (3.5 +/- 0.6) x 10(-4) s-1 for ferrocyanide. These results support models where multiple reactions are involved in complex processes leading to iron transfer and membrane translocation. A type II NADH dehydrogenase (diaphorase) is present on the endosome outer membrane. The kinetics of extravesicular ferricyanide reduction indicate a bimolecular-bimolecular steady-state mechanism with substrate inhibition. Ferricyanide inhibition of 59Fe mobilization is not detected. Significant differences between mobilization and ferricyanide reduction kinetics indicate that the diaphorase is not involved in 59Fe(III) reduction. Sequential additions of NADH followed by ascorbate or vice versa indicate a minimum of two sites of 59Fe(III) residence; one site available to reducing equivalents from ascorbate and a different site available to NADH. Sequential additions using ferrocyanide and the other reductants suggest interactions among sites available for reduction. Inhibition of ascorbate-mediated mobilization by DCCD and enhancement of ferrocyanide and NADH-mediated mobilization suggest a role for a moiety with characteristics of a proton pore similar to that of the H(+)-ATPase. These data provide significant constraints on models of iron reduction, translocation, and mobilization by endocytic vesicles.
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PMID:Kinetic characterization of reductant dependent processes of iron mobilization from endocytic vesicles. 153 18

A colorimetric microassay for the simultaneous quantitative determination of galactose (Gal) and galactose-1-phosphate (Gal-1-P) in dried blood spots is described. An enzymatic reaction involving alkaline phosphatase (EC 3.1.3.1) and galactose dehydrogenase (EC 1.1.1.48) produces NADH, which is coupled with diaphorase (EC 1.8.1.4) and iodonitrotetrazolium violet (INT). The colourless INT is converted to a formazan of red colour the intensity of which is quantitated either photometrically by a microplate reader or determined visually with sufficient sensitivity for screening purposes. We evaluated the assay on 200,000 blood samples in a newborn screening program, and were able to distinguish between classical and milder forms of galactosemia with ease.
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PMID:Colorimetric determination of galactose and galactose-1-phosphate from dried blood. 155 Dec 39

Eleven frostbites were induced on the ears of seven New Zealand White rabbits and specimens were taken from the lesion after 1, 4 and 8 hours, and from ten further frostbites on the ears of six rabbits for examination 1, 3 and 7 days later. The specimens were taken at the border between the frozen and non-frozen skin. NADH-diaphorase, alkaline phosphatase and esterase were demonstrated histochemically in the sample, which was also studied by haematoxylin and eosin staining. Five ears served as controls. Some granulocytes could be seen accumulating in the vessels and in the dermis at the border of the frostbite area after only 1 hour, and other enzyme rich cells (macrophages) also began to appear. After 4 hours the inflammation was quite obvious with the enzyme reactions clearly observable in the sections. After 8 hours there was no marked difference compared with the 4-hour picture. It was only after 3 days that the line of demarcation between the normal and frostbite tissue could be seen clearly. This was oblique in some specimens and vertical in others. The degeneration in the lesion could best be demonstrated by the NADH-diaphorase and esterase reactions and the early inflammation by the alkaline phosphatase reaction.
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PMID:Enzyme histochemical reactions at the demarcation line in frostbite: an experimental study on rabbits. 162 43

Formation of the nasal septal cartilage in prenatal and neonatal rats was studied histologically and by histochemistry to determine the manner, degree and participation of the nasal septal cartilage in midface growth and in bone formation of the face. Chondrogenesis of the nasal septal cartilage started at the 13th embryonic day, premaxillary and vomerin bone formation at the 14th embryonic day and endochondral bone formation of the septo-presphenoid area at the 17th embryonic day. After differentiation of the nasal septal cartilage, this cartilage supported ethmoid bone formation by endochondal ossification in the septo-presphenoid area. Nasal septal cartilage showed intense activity of lactate dehydrogenase, NADH2-diaphorase and a moderate activity of acid phosphatase, whereas premaxillary and vomerin bone showed intense activity of alkaline phosphatase. Osteoblasts showed intense activity of alkaline phosphatase, lactate dehydrogenase and NADH2-diaphorase and osteoclasts showed intense activity of acid phosphatase. During the embryonal period growth of the nasal septal cartilage could occur in an ethmoido-rostral direction supported by endochondral ossification and growth in length and height supported by apposition and interstitial growth.
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PMID:Histochemical analysis of enzymes involved in the formation and metabolism of the nasal septal cartilage. 163 42


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