Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.5.2 (NQO1)
 6,196 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

NAD(P)H dehydrogenase (EC 1.6.99.2) purified from rat liver cytosol revealed three discrete bands, of mol.wts. about 27000, 18000 and 9000, when subjected to polyacrylamidegel electrophoresis in the presence of sodium dodecyl sulphate. Elution of the bands from the gel and individual re-electrophoresis on separate gels showed that the 27000-mol.wt. band yielded three bands similar to those obtained with the intact enzyme, whereas the 18000-mol.wt. band retained its characteristic mobility. Amino acid analysis of native enzyme and protein extracted from each of the three bands from sodium dodecyl sulphate/polyacrylamide gels suggests that the native enzyme is composed of two subunits and that each subunit consists of two dissimilar non-covalently bound polypeptides, so that altogether the enzyme is composed of four polypeptides, two of mol.wt. 18000 and two of mol.wt. 9000. NAD(P)H dehydrogenase was active over a wide pH range with no sharp optimum. The same K(m) value for NADH but different values for V(max.) were obtained for the enzyme purified from Sprague-Dawley and Wistar rats. In immunodiffusion, however, the enzymes from the two rat strains showed a reaction of complete identity. NAD(P)H dehydrogenase was effectively inhibited by thiol-blocking reagents, indicating that the activity is dependent on free thiol group(s). By amino acid analysis six cysteine residues were found per mol of enzyme. Guanidino-group- and amino-group-selective reagents had only moderate inactivating effects on the enzyme activity.
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PMID:Some molecular properties of NAD(P)H dehydrogenase from rat liver. 48 48

Dihydrodiol dehydrogenase (DD; EC 1.3.1.20) will oxidize non-K-region trans-dihydrodiols of polycyclic aromatic hydrocarbons (PAHs), a reaction that can suppress the formation of PAHs) anti-diol epoxides or ultimate carcinogens. Using benzenedihydrodiol [(+/-)-trans-1,2-dihydroxy-3,5-cyclohexadiene] as a model substrate for trans-dihydrodiol metabolites of PAHs, 23 human liver and eight human lung samples were examined for enzyme activity. In human liver, enzyme activity could be measured spectrophotometrically and specific activities ranged from 0.16 to 6.1 nmol benzenedihydrodiol oxidized min/mg protein. Western blot analysis of human liver cytosol using rabbit anti-rat DD serum detected two bands of mol. wts 34,000 and 27,000. The former mol. wt is identical to that observed for the homogeneous rat liver enzyme. Gel-filtration experiments indicate that human liver DD activity elutes as a single peak and co-elutes with the purified rat liver enzyme, suggesting that the lower mol. wt species may be an artefact of degradation. Preparations of the human liver enzyme required NADP- for activity and were in general, insensitive to inhibition by dicoumarol, indomethacin and 6-medroxyprogesterone acetate. These properties distinguish the enzyme from alcohol dehydrogenase, quinone reductase and rat liver DD. In human lung, DD activity was barely detectable using a sensitive radiochemical assay in which the oxidation of benzenedihydrodiol to catechol is linked to catechol-O-methyl transferase using [3H]S-adenosyl methionine as methyl donor. Specific activities were approximately 1000th of that observed for human liver and ranged from 1 to 4 pmol benzenedihydrodiol oxidized/min/mg protein. Western blot analysis of lung cytosol detected three bands of mol. wts 34,000, 31,000 and 28,000. The relatively high levels of DD in human liver suggest that this enzyme may play an important role in PAH detoxication in this organ, while the low levels of DD in lung may contribute to the susceptibility of this tissue to PAH-induced carcinogenesis.
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PMID:Characterization of dihydrodiol dehydrogenase in human liver and lung. 219 14

To demonstrate the regional, cellular and subcellular distributions of non-N-methyl-D-aspartate glutamate receptors in rat brain, we generated antipeptide antibodies that recognize the C-terminal domains of individual subunits of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-preferring glutamate receptors (i.e. GluR1, GluR4, and a region highly conserved in GluR2, GluR3 and GluR4c). On immunoblots, antibodies detect distinct proteins with mol. wts ranging from 102,000 to 108,000 in homogenates of rat brain. Immunocytochemistry shows that glutamate receptor subunits are distributed abundantly and differentially within neuronal cell bodies and processes in cerebral cortex, basal ganglia, limbic system, thalamus, cerebellum and brainstem. The precise patterns and cellular localizations of glutamate receptor subunit immunoreactivities are unique for each antibody. In neocortex and hippocampus, pyramidal neurons express GluR1 and GluR2/3/4c immunoreactivities; many non-pyramidal, calcium-binding, protein-enriched neurons in cerebral cortex are selectively immunoreactive for GluR1. In striatum, the cellular localizations of GluR1, GluR2/3/4c and GluR4 immunoreactivities are different; in this region, GluR1 co-localizes with many cholinergic neurons but is only present in a minor proportion of nicotinamide adenine dinucleotide phosphate diaphorase-positive striatal neurons. GluR1 co-localizes with most dopaminergic neurons within the substantia nigra. In several brain regions, astrocytes show GluR4 immunoreactivity. Within the cerebellar cortex, cell bodies and processes of Bergmann glia express intense GluR4 and GluR1 immunoreactivities; perikarya and dendrites of Purkinje cells show GluR2/3/4c immunoreactivity but no evidence of GluR1 or GluR4. Ultrastructurally, GluR subunit immunoreactivities are localized within cell bodies, dendrites and dendritic spines of specific subsets of neurons and, in the case of GluR1 and GluR4, in some populations of astrocytes. This investigation demonstrates that individual AMPA-preferring glutamate receptor subunits are distributed differentially in the brain and suggests that specific neurons and glial cells selectively express glutamate receptors composed of different subunit combinations. Thus, the co-expression of all AMPA receptor subunits within individual cells may not be obligatory for the functions of this glutamate receptor in vivo.
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PMID:AMPA glutamate receptor subunits are differentially distributed in rat brain. 838 83