Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q8NEX9 (reductase)
 26,410 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Using quantitative histochemical techniques, it was determined that the tensor tympani muscle of the cat consists of three muscle fiber types: type 1, type 2A (staining characteristics similar to the type 1 and type 2A muscle fibers found in the control tibialis anterior muscles), and a third unclassified fiber type (type 3) similar to the 2A fiber type except that it had extremely dense alkaline actomyosin adenosine triphosphatase staining (mean transmittance, type 2A = 33.6%; type 3 = 17.3%), as well as dense staining for periodic acid-Schiff, menadione-linked alpha-glycerolphosphate dehydrogenase, nicotinamide-adenine dinucleotide tetrazolium reductase, and succinic dehydrogenase. The type 1 fiber population was smaller in diameter (mean +/- SD, 14 +/- 4 microns) than the type 2A fiber (mean +/- SD, 21 +/- 5 microns) and the type 3 fiber (mean +/- SD, 22 +/- 6 microns) populations. In all muscles, intrafascicular and extrafascicular fat accumulations were found, with the majority being extrafascicular. Calculations indicate that the tendon occupies approximately 41% of the total muscle volume, while the muscle fibers constitute 59% of the volume.
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PMID:Muscle fiber types in the cat middle ear muscles. II. Tensor tympani. 296 26

The purpose of this study was to determine histologically the distribution of microspheres (MSs) (14 micron), and hence the relative distribution of blood flow, in rat plantaris muscle relative to the fiber types (fast-twitch-oxidative-glycolytic [FOG], fast-twitch-glycolytic [FG], and slow-twitch-oxidative [SO]). Three conditions were investigated: 1) preexercise standing; 2) treadmill locomotion at 15 m/min (fast walking); and 3) treadmill locomotion at 60 m/min (moderate galloping). The MS suspension (containing 1 x 10(6) MSs) was infused into the ascending aorta via a catheter in the carotid artery under each of the 3 conditions so that MSs were distributed to the tissues in proportion to their respective blood flows. Sections (20 micron) of the plantaris muscle were cut and assayed for reduced nicotinamide adenine dinucleotide tetrazolium reductase (NADH-TR) and myofibrillar adenosine triphosphatase (ATPase) activities so the fibers could be typed as SO, FOG, or FG. MSs were located in the NADH-TR sections, and the fibers next to the MSs were classified and counted. The observed numbers of fibers of each type in each condition that were adjacent to MSs were compared to the predicted number of adjacent fibers based on the assumption the MSs were randomly distributed in the tissue. This analysis demonstrated that MSs (and blood flows) were preferentially distributed to SO fibers during preexercise, to SO and FOG fibers during slow locomotion, and to FOG fibers during fast locomotion. The data support the contention that blood flow is distributed in muscles of conscious animals as functions of fiber type and exercise intensity.
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PMID:Distribution of microspheres in plantaris muscles of resting and exercising rats as a function of fiber type. 297 25

The spatial relationships between the four reduced nicotinamide adenine dinucleotide phosphate (NADPH) binding sites on chicken liver fatty acid synthase were explored with electron paramagnetic resonance (EPR) and spin-labeled analogues of NADP+. The analogues were prepared by reaction of NADP+ with 2,2,5,5-tetramethyl-1-oxy-3-pyrroline-3-carboxylic acid, with 1,1'-carbonyldiimidazole as the coupling reagent. Several esterification products were characterized, and the interaction of the N3' ester of NADP+ with the enzyme was examined in detail. Both 1H13, 14N and 2H13, 15N spin-labels were used: the EPR spectrum was simpler, and the sensitivity greater, for the latter. The spin-labeled NADP+ is a competitive inhibitor of NADPH in fatty acid synthesis, and an EPR titration of the enzyme with the modified NADP+ indicates four identical binding sites per enzyme molecule with a dissociation constant of 124 microM in 0.1 M potassium phosphate and 1 mM ethylenediaminetetraacetic acid (pH 7.0) at 25 degrees C. The EPR spectra indicate the bound spin-label is immobilized relative to the unbound probe. No evidence for electron-electron interactions between bound spin-labels was found with the native enzyme, the enzyme dissociated into monomers, or the enzyme with the enoyl reductase sites blocked by labeling the enzyme with pyridoxal 5'-phosphate. Furthermore, the EPR spectrum of bound ligand was the same in all cases. This indicates that the bound spin-labels are at least 15 A apart, that the environment of the spin-label at all sites is similar, and that the environment is not altered by major structural changes in the enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Interaction of spin-labeled nicotinamide adenine dinucleotide phosphate with chicken liver fatty acid synthase. 302 Nov 96

The properties of the interactions of anticancer quinone drugs, aclacinomycin A, adriamycin, carbazilquinone, and mitomycin C with nicotinamide adenine dinucleotide phosphate (NADPH)-cytochrome P-450 reductase and xanthine oxidase under anaerobic and aerobic conditions were studied. Km values of NADPH-cytochrome P-450 reductase for these drugs were in the range of 40-227 microM, and that of deflavo xanthine oxidase in the range of 39-over 200 microM. Under anaerobic conditions, when xanthine was used as an electron donor, deflavo xanthine oxidase catalyzed the reductive glycosidic cleavage reaction of anthracyclines and nicotinamide adenine dinucleotide was ineffective as an electron donor. In the electron spin resonance study, the formation of the semiquinone or free radical state of the quinone drugs in both enzyme systems were evidenced. A weak and symmetric signal was obtained from aclacinomycin A, and a symmetric signal from adriamycin was changed into an asymmetric and strong. The hyperfine structure was obtained from carbazilquinone in the oxidase system. In the studies of ultraviolet-visible spectra of the quinone drugs in the reductase system, the spectra of aclacinomycin A and adriamycin were changed to their 7-deoxylaglycones, and the formation of small amounts of the fully reduced form were observed after long incubations. The spectrum of carbazilquinone was changed to the hydroquinone form and mitomycin C was converted into mitosene analogues. Under aerobic conditions, superoxide radicals and hydrogen peroxide were effectively produced in the presence of anticancer quinone drugs in both enzyme systems. The superoxide-dependent hydroxy radical production, which was measured by ethylene production from methional, was observed in the presence of aclacinomycin A and adriamycin in the deflavo xanthine oxidase system. From these results, the possible reactions in the interactions of anticancer quinone drugs with these enzymes and oxygen are discussed.
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PMID:Interactions of anticancer quinone drugs, aclacinomycin A, adriamycin, carbazilquinone, and mitomycin C, with NADPH-cytochrome P-450 reductase, xanthine oxidase and oxygen. 302

A procaryotic high-level expression vector for human dihydrofolate reductase has been constructed and the protein characterized as a first step toward structure-function studies of this enzyme. A vector bearing the tac promoter, four synthetic oligodeoxynucleotides, and a restriction fragment from the dihydrofolate reductase cDNA were ligated in a manner which optimized the transcriptional and translational frequency of the enzyme mRNA. The reductase, comprising ca. 17% of the total soluble protein in the host bacteria, was purified to apparent homogeneity as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and characterized by amino acid composition, partial amino acid sequence, and steady-state kinetic analysis. This expression vector has been used as a template for double-stranded plasmid DNA site-specific mutagenesis. Functional studies on a Cys-6----Ser-6 mutant enzyme support the contention that Cys-6 is obligatory for organomercurial activation of human dihydrofolate reductase. The Ser-6 mutant enzyme was not activated to any extent following a 24-h incubation with p-(hydroxymercuri)benzoate and nicotinamide adenine dinucleotide phosphate (reduced) (NADPH), whereas the kcat for Cys-6 reductase increased 2-fold under identical conditions. The specific activities of the Cys-6 and Ser-6 enzymes were virtually identical as determined by methotrexate titration as were the Km values for both dihydrofolate and NADPH. The Ser-6 mutant showed a decreased temperature stability and was more sensitive to inactivation by alpha-chymotrypsin when compared to the wild-type enzyme. These results suggest that the Ser-6 mutant reductase is conformationally altered relative to the Cys-6 native enzyme.
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PMID:Expression and site-directed mutagenesis of human dihydrofolate reductase. 304 47

The in vitro metabolism of marcellomycin by rat tissue fractions showed conversion of marcellomycin to 7-deoxypyrromycinone, bisanhydropyrromycinone, and an as yet unidentified compound by rat liver homogenate, microsomes, cytosol, and mitochondria, and purified hepatic reduced nicotinamide adenine dinucleotide phosphate-cytochrome P-450 reductase, under anaerobic conditions and in the presence of reduced nicotinamide adenine dinucleotide phosphate. All these fractions except the purified reductase subsequently induced a progressive loss of fluorescence. Mitochondria, however, were much less active than microsomes, cytosol, and homogenate in inducing this latter phenomenon. Marcellomycin was converted to 7-deoxyaglycones only partially by nuclei. No loss of fluorescence was observed with this subcellular fraction. No loss of fluorescence was observed when doxorubicin or daunorubicin were incubated under similar conditions. The appearance of a compound with distinct spectrophotometric properties was demonstrated by absorbance spectrometry. The formation of a compound with different fluorescent characteristics was excluded, as was the binding of the aglycones to subcellular components. The activity inducing the loss of fluorescence was studied in greater detail with cytosol. It predominated in the liver and required both an electron donor and anaerobic conditions. The optimal pH for the reaction was between 7.5 and 8.0. Our results suggest the existence of an enzymatic pathway capable of converting the fluorescent nucleus of marcellomycin to a nonfluorescent metabolite.
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PMID:Comparative anthracycline metabolism in rats: loss of marcellomycin fluorescence. 308 76

Interpretation of primary monolayer culture of organs and tissues with different epithelial cell types demands well-defined criteria for distinguishing between such cells. Epithelial components in breast carcinomas comprise, in addition to carcinoma epithelial cells (CEP), at least two epithelial cell types organized in mammary ductules of normal appearance as an inner layer of luminal epithelial cells (LEP) and an outer layer of basal or myoepithelial cells (MEP) resting on a basement membrane. In a previous study (Petersen and van Deurs, Cancer Res., 46: 2013-2020, 1986) we have defined a population of CEP in vivo and in vitro, appearing in about 50% of primary carcinomas, by a cytochemical reaction for reduced nicotinamide adenine dinucleotide phosphate neotetrazolium reductase. Carcinoma derived epithelial cells not showing this cytochemical reaction in culture were believed to originate from either carcinoma cells or from mammary ductules of normal or benign appearance. In the present study we show that carcinoma derived NADPH-NT reductase negative cell islets often exhibit phenotypic traits of apparently normal mammary ductules as defined in vivo. Moreover, it is shown that the reductase positive CEP, apart from the reductase reaction, has preserved several other features in culture distinguishing them from cells of apparently normal origin. Thus, whereas reductase positive CEP often consisted of only one cell type, as revealed by phase contrast microscopy, some reductase negative cell islets showed a distinct two-cell-type composition. One cell type exhibited cobblestone-like appearance and remained in the center of the islets whereas the other was more loosely arranged and rapidly left the central area by migration below the cobblestone-like cells to the periphery of the islets. Cobblestone-like cells and loosely arranged cells were found by immunocytochemistry to express elements of LEP and MEP phenotype, respectively. LEP phenotype was defined in vivo by expression of milk fat globule membrane antigen and cytokeratins, whereas MEP expressed basement membrane-associated type IV collagen. Computerized image analysis revealed mean population doubling times for cells with MEP phenotype of 1 day and for those with LEP phenotype of 2 days. Both cell types showed a diploid DNA pattern as revealed by fluorimetry. Reduced nicotinamide adenine dinucleotide phosphate neotetrazolium reductase positive CEP expressed milk fat globule membrane antigen and cytokeratins, thus resembling the reductase negative LEP.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Preservation of defined phenotypic traits in short-term cultured human breast carcinoma derived epithelial cells. 310 27

The enzyme that catalyzes the ADP-ribosylation and concomitant inactivation of dinitrogenase reductase in Rhodospirillum rubrum has been purified greater than 19,000-fold to near homogeneity. We propose dinitrogenase reductase ADP-ribosyltransferase (DRAT) as the working name for the enzyme. DRAT activity is stabilized by NaCl and ADP. The enzyme is a monomer with a molecular mass of 30 kDa and is a different polypeptide than dinitrogenase reductase activating glycohydrolase. NAD (Km = 2 mM), etheno-NAD, nicotinamide hypoxanthine dinucleotide, and nicotinamide guanine dinucleotide will serve as donor molecules in DRAT-catalyzed ADP-ribosylation reaction, and dinitrogenase reductases from R. rubrum, Azotobacter vinelandii, Klebsiella pneumoniae, and Clostridium pasteurianium will serve as acceptors. No other proteins or small molecules, including water, have been found to be effective as acceptors. Nicotinamide is released stoichiometrically with formation of the ADP-ribosylated product. DRAT is inhibited by NaCl and has maximal activity at a pH of 7.0.
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PMID:Purification and properties of dinitrogenase reductase ADP-ribosyltransferase from the photosynthetic bacterium Rhodospirillum rubrum. 314 11

Comparisons were made of the histochemical characteristics of skeletal muscle from 10 animal species. The basic comparison was made from the staining patterns for the myofibrillar actomyosin ATPase produced by preincubation of fresh frozen cross-sections of muscle at alkaline pH (10.30) or acid pH (4.60) with those produced by preincubation in media containing Cu2+ at alkaline pH (10.30), near neutral pH (7.40), or acid pH (4.60). Muscle sections were also stained for reduced nicotinamide adenine dinucleotide tetrazolium reductase and alpha-glycerophosphate dehydrogenase to provide an indication of the relative oxidative and glycolytic capacity of the different fiber types. Type II fibers in mixed fibered muscles were either very sensitive, moderately sensitive, or relatively insensitive to inactivation of the myofibrillar actomyosin ATPase after acid preincubation. These fibers were identified as type IIA1, IIA2, and IIA3, respectively. The myofibrillar actomyosin ATPase of the type I fibers of these muscles, with the exception of those in mouse muscle, was activated by pretreatment with acid. A separation of animal species was possible based on the stability of the IIA1 fibers to inclusion of Cu2+ in the preincubation medium. For one group of animals (rat, mouse, monkey, man, dog, rabbit, and cow), a reciprocal relationship existed between lability to acid and stability to Cu2+ for type IIA1 and IIA3 fibers, respectively. For the second group of animals (horse, ass, and cat) there was a parallel relationship between lability or stability of the type IIA1 and IIA3 fibers to pretreatment with either acid or Cu2+.
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PMID:Comparison of fiber types in skeletal muscles from ten animal species based on sensitivity of the myofibrillar actomyosin ATPase to acid or copper. 315 28

The purpose of this study was to determine whether 8-12 wk of endurance training produces biochemical and histochemical adaptations in skeletal muscle in foxhounds. Analyses were performed on samples removed from gastrocnemius, triceps, and semitendinosus muscles of foxhounds before and after a treadmill running program. Biochemical analysis showed that training did not alter the activities of phosphofructokinase, beta-hydroxyacyl-CoA dehydrogenase, succinate dehydrogenase, or total phosphorylase. Histochemical analysis of myofibrillar actomyosin ATPase demonstrated three distinct classes of type II fibers and one type I fiber in the semitendinosus and triceps muscles and two type II and two type I fibers in the gastrocnemius muscle. Fiber type distribution and oxidative and glycolytic potentials, as indicated by nicotinamide adenine dinucleotide tetrazolium reductase or alpha-glycerophosphate dehydrogenase staining intensity, were unaltered by training. Similarly, capillary density, capillary-to-fiber ratios, and capillary area-to-fiber area ratios did not change with training. Thus, unlike humans and other mammals (i.e., rat), these foxhounds did not manifest biochemical or histochemical adaptations in skeletal muscle as the result of endurance training. This is consistent with the results of the study in which endurance training produced a 27% increase in maximal cardiac output and a 4% increase in maximal arteriovenous O2 extraction in foxhounds.
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PMID:Dynamic exercise training in foxhounds. II. Analysis of skeletal muscle. 316 58


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