Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.10.3.1 (tyrosinase)
 9,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Biotin deficiency resulted in an increased growth rate of Aspergillus nidulans. The activities of hexokinase and aldolase were not much changed during the growth cycle, but activities of glucose-6-phosphate dehydrogenase and NADP-linked glutamate dehydrogenase increased significantly during the exponential phase. This change was remarkable during biotin deficiency. In contrast to the higher growth rate and respiration rate during biotin deficiency the activities of NAD(P)H oxidoreductases were low. An inverse relationship between the activity of tyrosinase and melanin content was observed. A role of the DOPA-DOPA-quinone system in maintaining culture growth is suggested.
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PMID:Growth, glucose metabolism and melanin formation in biotin-deficient Aspergillus nidulans. 40 7

The dermal cells in grey, xanthic, and white goldfish integuments were cytochemically characterized for the following enzymatic activities: tyrosinase, DOPA-oxidase, cytochrome oxidase, monoamine oxidase, peroxidase, non-specific esterase, cholinesterase, NAD-diaphorase, NADP-diaphorase, aryl sulfatase, nucleotide phosphodiesterase, beta-glucuronidase, acid phosphatase, alkaline phosphatase, adenosine triphosphatase, thiamine pyrophosphatase, glucose-6-phosphatase, aldolase, as well as succinate, malate, isocitrate, glutamate, glucose-6-phosphate, 6-phosphogluconate, alpha-glycerophosphate, alcohol, lactate, and beta-hydroxybutyrate dehydrogenases. It was found that the epidermis was a significant barrier to the access of cytochemical reaction substrates. Removal of the epidermal barrier provided dermal cell localizations of enzymatic activities which were reproducible. Further, alterations in reaction times and temperatures from the mammalian methodology provided conditions fe various integumental cells were compared for possible interrelationships. The basic foundations for future work with the dermis of poikilothermic vertebrates on an experimental basis were established. In addition, a previously undescribed non-pigmented dermal cell, the "x"-cell, was found to have enzymatic characteristics similar to both melanophores and lipophores. The "x"-cell may be the common precursor of both types of pigment cells.
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PMID:Cytochemical characterization of goldfish (Carassius auratus L.) dermis with special reference to the pigment cells. 82 86

In vitro experiments are reported showing that NAD(P)H:(quinone acceptor) oxidoreductase (QR), purified from Glycine max seedlings, reduces Leu- and Met-enkephalin-tyrosinase oxidation products, in the presence of NADH or NADPH. QR was not capable to catalyze the reduction of N-acetyl-dopaquinone formed by the cation of mushroom tyrosinase on N-acetyl-L-tyrosine, while it was able to reduce dopachrome. The results support the hypothesis that QR can inhibit the formation of melanin-like compounds, as catalyzed by the action of tyrosinase on Leu-enkephalin and Met-enkephalin. It is proposed that, in the presence of NAD(P)H as the electron donor, the inhibition occurs by the specific conversion of the dopachrome-derivative into the reduced precursor, leucodopachrome-derivative.
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PMID:Effect of NAD(P)H:quinone oxidoreductase on tyrosinase-mediated oxidation of opioid neuropeptides Leu-enkephalin and Met-enkephalin. 867 15

Graphite electrodes fabricated by screen-printing have been used as amperometric detectors in biosensors based on NAD(+)-dependent dehydrogenases, tyrosinase, or genetically modified acetylcholinesterases. The mono-enzyme sensors have been optimized as disposable or reusable devices for detection of a variety of substrates important in the food industry ( D-lactic acid, L-lactic acid, acetaldehyde) or in environmental pollution control (phenols and dithiocarbamate, carbamate and organophosphorus pesticides). The sensors were prepared in four configurations differing in enzyme confinement, enzyme immobilization and location of the immobilization agent in the biosensor assembly. Tests on real samples have been performed with the biosensors; D-lactic acid and acetaldehyde have been detected in wine and phenols in air.
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PMID:Biosensors designed for environmental and food quality control based on screen-printed graphite electrodes with different configurations. 1220 36

A tyrosinase-directed therapeutic approach for treating malignant melanoma uses depigmenting phenolic prodrugs such as 4-hydroxyanisole (4-HA) for oxidation by melanoma tyrosinase to form cytotoxic o-quinones. However, in a recent clinical trial, both renal and hepatic toxicity were reported as side effects of 4-HA therapy. In the following, 4-HA (200 mg/kg i.p.) administered to mice caused a 7-fold increase in plasma transaminase toxicity, an indication of liver toxicity. Furthermore, 4-HA induced-cytotoxicity toward isolated hepatocytes was preceded by glutathione (GSH) depletion, which was prevented by cytochrome p450 inhibitors that also partly prevented cytotoxicity. The 4-HA metabolite formed by NADPH/microsomes and GSH was identified as a hydroquinone mono-glutathione conjugate. GSH-depleted hepatocytes were much more prone to cytotoxicity induced by 4-HA or its reactive metabolite hydroquinone (HQ). Dicumarol (an NAD(P)H/quinone oxidoreductase inhibitor) also potentiated 4-HA- or HQ-induced toxicity whereas sorbitol, an NADH-generating nutrient, prevented the cytotoxicity. Ethylenediamine (an o-quinone trap) did not prevent 4-HA-induced cytotoxicity, which suggests that the cytotoxicity was not caused by o-quinone as a result of 4-HA ring hydroxylation. Deferoxamine and the antioxidant pyrogallol/4-hydroxy-2,2,6,6-tetramethylpiperidene-1-oxyl (TEMPOL) did not prevent 4-HA-induced cytotoxicity, therefore excluding oxidative stress as a cytotoxic mechanism for 4-HA. A negligible amount of formaldehyde was formed when 4-HA was incubated with rat microsomal/NADPH. These results suggest that the 4-HA cytotoxic mechanism involves alkylation of cellular proteins by 4-HA epoxide or p-quinone rather than involving oxidative stress.
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PMID:Metabolic activation of 4-hydroxyanisole by isolated rat hepatocytes. 1222 81

A tyrosinase-directed therapeutic approach for malignant melanoma therapy uses the depigmenting phenolic agents such as 4-hydroxyanisole (4-HA) to form cytotoxic o-quinones. However, renal and hepatic toxicity was reported as side effects in a recent 4-HA clinical trial. In search of novel therapeutics, the cytotoxicity of the isomers 4-HA, 3-HA and 2-HA were investigated. In the following, the order of the HAs induced hepatotoxicity in mice, as measured by increased in vivo plasma transaminase activity, or in isolated rat hepatocytes, as measured by trypan blue exclusion, was 3-HA > 2-HA > 4-HA. Hepatocyte GSH depletion preceded HA induced cytotoxicity and a 4-MC-SG conjugate was identified by LC/MS/MS mass spectrometry analysis when 3-HA was incubated with NADPH/microsomes/GSH. 3-HA induced hepatocyte GSH depletion or GSH depletion when 3-HA was incubated with NADPH/microsomes was prevented by CYP 2E1 inhibitors. Dicumarol (an NAD(P)H: quinone oxidoreductase inhibitor) potentiated 3-HA- or 4-methoxycatechol (4-MC) induced toxicity whereas sorbitol (an NADH generating nutrient) greatly prevented cytotoxicity indicating a quinone-mediated cytotoxic mechanism. Ethylendiamine (an o-quinone trap) largely prevented 3-HA and 4-MC-induced cytotoxicity indicating that o-quinone was involved in cytotoxicity. Dithiothreitol (DTT) greatly reduced 3-HA and 4-MC induced toxicity. The ferric chelator deferoxamine slightly decreased 3-HA and 4-MC induced cytotoxicity whereas the antioxidants pyrogallol or TEMPOL greatly prevented the toxicity suggesting that oxidative stress contributed to 3-HA induced cytotoxicity. In summary, ring hydroxylation but not O-demethylation/epoxidation seems to be the bioactivation pathway for 3-HA in rat liver. The cytotoxic mechanism for 3-HA and its metabolite 4-MC likely consists cellular protein alkylation and oxidative stress. These results suggest that 3-HA is not suitable for treatment of melanoma.
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PMID:Metabolic activation of 3-hydroxyanisole by isolated rat hepatocytes. 1245 69

The present work aims to evaluate Brown 3 REL degrading potential of developed microbial consortium GG-BL using two microbial cultures, Galactomyces geotrichum MTCC 1360 (GG) and Brevibacillus laterosporus MTCC 2298 (BL). Microbial consortium GG-BL showed 100% decolorization of a dye Brown 3 REL, while individually G. geotrichum MTCC 1360 and B. laterosporus MTCC 2298 showed 26% and 86% decolorization under aerobic condition (shaking) respectively. Measurements of biochemical oxygen demand (BOD) (76%) and chemical oxygen demand (COD) (68%) were done after decolorization by consortium GG-BL. No induction in activities of oxidoreductive enzymes found in G. geotrichum while B. laterosporus showed induction of veratryl alcohol oxidase, Nicotineamide adenine dinucleotide-dichlorophenol indophenol (NADH-DCIP) reductase and riboflavin reductase indicating their role in dye metabolism. Consortium GG-BL showed induction in the activities of laccase, veratryl alcohol oxidase, tyrosinase, NADH-DCIP reductase and riboflavin reductase. Two different sets of induced enzymes from G. geotrichum and B. laterosporus work together in consortium GG-BL resulting in faster degradation of dye. The degradation of Brown 3 REL was analyzed using high performance thin layer chromatography (HPTLC), high performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FT-IR) and gas chromatography mass spectroscopy (GC-MS). Phytotoxicity study revealed that metabolites formed after degradation was significantly less toxic in nature.
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PMID:Differential fate of metabolism of a disperse dye by microorganisms Galactomyces geotrichum and Brevibacillus laterosporus and their consortium GG-BL. 2351 51

Rhododendrol (RD) is a potent tyrosinase inhibitor that is metabolized to RD-quinone by tyrosinase, which may underlie the cytotoxicity of RD and leukoderma of the skin that may result. We have examined how forced expression of the NAD(P)H quinone dehydrogenase, quinone 1 (NQO1), a major quinone-reducing enzyme in cytosol, affects the survival of RD-treated cells. We found that treatment of the mouse melanoma cell line B16BL6 or normal human melanocytes with carnosic acid, a transcriptional inducer of the NQO1 gene, notably suppressed the cell killing effect of RD. This effect was mostly abolished by ES936, a highly specific NQO1 inhibitor. Moreover, conditional overexpression of the human NQO1 transgene in B16BL6 led to an expression-dependent increase of cell survival after RD treatment. Our results suggest that NQO1 attenuates the cytotoxicity of RD and/or its metabolites.
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PMID:NAD(P)H dehydrogenase, quinone 1 (NQO1), protects melanin-producing cells from cytotoxicity of rhododendrol. 2684 26

Developing anti-melanoma agents with increased activity and specificity is highly desirable due to the increasing incidence, highly metastatic malignancy, and high mortality rate of melanoma. Abnormal redox characteristics such as higher levels of tyrosinase, NAD(P)H: quinone oxidoreductase-1 (NQO1) and reactive oxygen species (ROS) observed in melanoma cells than in other cancer cells and normal cells illustrate their redox vulnerability and have opened a window for developing prooxidative anti-melanoma agents (PAAs) to target the vulnerability. However, how to design PAAs which promote selectively the ROS accumulation in melanoma cells remains a challenge. This work describes a promising redox cycle-based strategy for designing a catechol-type diphenylbutadiene as such type of PAA. This molecule is capable of constructing an efficient catalytic redox cycle with tyrosinase and NQO1 in melanoma B16F1 cells to induce selectively the ROS (mainly including hydrogen peroxide, H2O2) accumulation in the cells, resulting in highly selective suppression of melanoma B16F1 cells over tyrosinase-deficient HeLa and normal L-02 cells.
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PMID:A promising redox cycle-based strategy for designing a catechol-type diphenylbutadiene as a potent prooxidative anti-melanoma agent. 3045 79

Verticillium dahliae colonizes vascular tissue and causes vascular discoloration in susceptible hosts. Two well-defined races exist in V. dahliae populations from tomato and lettuce. In this study, proteins and metabolites obtained from stems of race 1-incompatible (Beefsteak) and -compatible (Early Pak) tomato cultivars were characterized. A total of 814 and 584 proteins in Beefsteak; and 456 and 637 proteins in Early Pak were identified in stem extracts of plants inoculated with races 1 and 2, respectively. A significant number of defense-related proteins were expressed in each tomato-V. dahliae interaction, as anticipated. However, phenylalanine ammonia-lyase (PAL), an important defense-associated enzyme of the phenylpropanoid pathway, in addition to remorin 1, NAD-dependent epimerase/dehydratase, and polyphenol oxidase were uniquely expressed in the incompatible interaction. Compared with the uninoculated control, significant overexpression of gene ontology terms associated with lignin biosynthesis, phenylpropanoid pathway and carbohydrate methylation were identified exclusively in the incompatible interaction. Phenolic compounds known to be involved in plant defense mechanisms were at higher levels in the incompatible relative to the compatible interactions. Based on our findings, PAL and enzymes involved defense-related secondary metabolism and the strengthening of cell walls is likely critical to confer resistance to race 1 of V. dahliae in tomato. SIGNIFICANCE: Verticillium dahliae, a soilborne fungal pathogen and a widely distributed fungal pathogen, colonizes vascular tissue and causes vascular discoloration in roots and stems, leaf wilting, and death of susceptible plant hosts. It causes billions of dollars in annual crop losses all over the world. The study focused on the proteomic and metabalomic of V. dahliae interactions (incompatible with Beefsteak and compatible with Early Pak tomato cultivars). Based on our findings, PAL and enzymes involved defense-related secondary metabolism and the strengthening of cell walls is likely critical to confer resistance to race 1 of V. dahliae in tomato.
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PMID:Proteome and metabolome analyses reveal differential responses in tomato -Verticillium dahliae-interactions. 3132 24


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