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:1.10.3.1 (tyrosinase)
9,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transplantable mouse melanomas possess a melanotropin-sensitive adenylate cyclase system which is responsive to alpha-melanotropin, beta-melanotropin, adrenocorticotropin (ACTH) and prostaglandin E1. It was found that sensitivity to ACTH was not directed towards the ACTH activity but to the intrinsic melanotropin activity of the ACTH molecule. Therefore, the melanotropin-sensitive adenylate cyclase system is hormonally specific to the intrinsic melanotropin activity of peptide hormones and is unique in the melanoma tissue. The significance of the sensitivity to prostaglandin E1 is obscure at present. The melanotropin-sensitive adenylate cyclase requires the presence of Mg2+ or Mn2+, for its enzymic activity. Ca2+ inhibit the enzyme in the presence of a wide range of concentrations of Mg2+. The enzymic activity is ATP concentration-dependent and the saturation concentration appears to be 1 mM. The enzyme is very labile in the unfractionated tumor homogenates. A washed 11000 X g particulate fraction, representing about 30-60% of the total enzymic activity, was found to be more stable and could be stored at 5 degrees C for 2 h without appreciable loss of the activity. This fraction retained sensitivity to melanotropin, prostaglandin E1 and NaF. About 20% of the activity of the tumor homogenate could not be sedimented by centrifugation at 105000 X g for 60 min. This "soluble" fraction was not responsive to melanotropin, prostaglandin E1 and NaF and might be a degradative product produced by the fractionation. Cyclic AMP and alpha-melanotropin were able to increase the tyrosinase activity of isolated mouse melanoma-cells in vitro under the same conditions.
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PMID:PHrmonal specificity of the melanotropin-sensitive adenylate cyclase of mouse melanoma and effect of cyclic AMP on the tyrosinase activity of mouse melanoma cells, in vitro. 0 31

The effects of 3'-5' cyclic AMP and ATP upon tyrosinase induction in Neurospora crassa were examined. Northern analysis of total cellular RNA revealed rapid de novo synthesis of protyrosinase after addition of these substances to stationary-phase mycelia. The maturation of protyrosinase in crude extracts of mycelia was followed by Western analysis. Polyclonal rabbit antiserum directed against the denatured carboxyl-terminal extension of protyrosinase does recognize the proform and several intermediate forms of different molecular weight but not mature tyrosinase. Disruption of ATP-induced mycelia in sodium phosphate buffer (pH 6.0) demonstrate processing at the carboxyl-terminal end of protyrosinase. The activity assays revealed that protyrosinase is an inactive precursor and that at least two active forms of slightly different molecular weight are present in crude extracts. Maturation of protyrosinase thus involves specific and sequential proteolytic cleavage at the carboxyl-terminus. These results suggest the presence of a tyrosinase activator in Neurospora crassa mycelia, which is kept apart from protyrosinase in the intact mycelium.
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PMID:ATP-induced protyrosinase synthesis and carboxyl-terminal processing in Neurospora crassa. 215 Feb 29

A 64-kDa protein was purified from an octyl glucoside/cholate extract of spinach thylakoids. N-Terminal analysis yielded 23 residues of sequence, of which the first 15 were identical to a sequence reported [Gal, A., Herrmann, R. G., Lottspeich, F., & Ohad, I. (1992) FEBS Lett. 298, 33-35] for a protein kinase with specificity toward the photosystem II light-harvesting complex (LHC-II). We report the complete sequence of this 64-kDa protein, deduced from cDNA clones. The transit peptide has a chloroplast import signal at the N-terminus and a C-terminal hydrophobic span bounded by basic amino acids that predicts localization of the protein to the thylakoid lumen. The mature protein sequence is about 50% identical to several polyphenol oxidases (PPOs). Canonical protein kinase motifs are absent, as are sequences characteristic of ATP-binding sites. The mature protein resembles arthropodan hemocyanin (Hc), possessing three major domains. The N-terminal domain is rich in cysteine residues and predicted alpha-helices. The central domain has a conserved motif, N-terminal to a presumptive Cu-A site, that is not found in tyrosinases or Hc and is proposed as the provider of a third imidazole ligand to Cu-A. An unusual 13-residue, glutamine-rich link begins a C-terminal domain containing 7 predicted beta-strands which, by analogy with Hc, may form an antiparallel beta-barrel. We conclude that this 64-kDa polypeptide is a lumenal PPO and the precursor of a 42.5-kDa PPO form described previously [Golbeck, J. H., & Cammarata, K. V. (1981) Plant Physiol. 67, 977-984].(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Spinach thylakoid polyphenol oxidase: cloning, characterization, and relation to a putative protein kinase. 779 29

A tomato (Lycopersicon esculentum L.) gene encoding a precursor of polyphenol oxidase (PPO) was transcribed and translated in vitro. The import, targeting, and processing of the [35S]methionine-labeled precursor protein (pPPO) were studied in isolated chloroplasts. The protein was routed to the thylakoid lumen in two steps. The 67-kD precursor was first imported into the stroma in an ATP-dependent step. It was processed to a 62-kD intermediate by a stromal peptidase. Translocation into the lumen was light dependent and involved processing of the 62-kD to the 59-kD mature form. The mature polypeptide was soluble in the lumen and not bound to thylakoids. This two-step targeting pattern was observed in plastids from a variety of plants including pea (Pisum sativum L.), tomato, and maize (Zea mays L.). The ratio between the intermediate and mature forms observed depended on the plant species, leaf age, growth conditions, and illumination regime to which the plants had been subjected. Cu2+ was not required for pPPO import or processing. Furthermore, low concentrations of Cu2+ (1-5 microM) markedly inhibited the first import step. Tentoxin specifically inhibited pPPO import, leaving the precursor bound to the envelope membrane. The two-step routing of pPPO into chloroplasts, typical of thylakoid lumen proteins, is consistent with the two-domain structure of the transit peptide and appears to be a feature of all plant PPO genes isolated so far. No evidence was found for unorthodox routing mechanisms, which have been suggested to be involved in the import of plant PPOs. The two-step routing may account for some of the multiplicity of PPO observed in vivo.
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PMID:Import, targeting, and processing of a plant polyphenol oxidase. 797 97

Twelve analogues of the antibacterial phenolic peptide 5-S-glutathionyl-N-beta-alanyl-L-dopa (5-S-GA-L-D, 1) were synthesized via orthoquinone using tyrosinase. Several synthesized compounds inhibited the v-Src autophosphorylation tyrosine kinase reaction with an IC50 value comparable to that of herbimycin A. The inhibition of c-Src substrate phosphorylation was much less active than v-Src autophosphorylation inhibition. 5-S-GA-L-D (1) and its analogous competed with peptide substrate and non-compared with ATP. The analogues showed no effects on substrate phosphorylation by epidermal growth factor receptor (EGFR), and this selectivity is the most characteristic feature of the 5-S-GA-L-D and its analogues (1-12).
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PMID:Inhibition effects of 5-S-glutathionyl-N-beta-alanyl-L-dopa analogues against Src protein tyrosine kinase. 1039 35

Cinnamoyl, p-coumaroyl, feruloyl, caffeoyl aloesin, and related compounds were isolated from Aloe species. The antiinflammatory and antioxidative activities of these compounds were examined based on the structure-activity relationship. It was suggested that the bioactivities may link to acyl ester groups in aloesin, together with those of aloesin-related compounds. However, investigations using the contact hypersensitivity response indicated a preventive effect of aloesin on the UV-B-induced immune suppression. Furthermore, aloesin inhibited tyrosine hydroxylase and dihydroxyphenylalanine (DOPA) oxidase activities of tyrosinase from normal human melanocyte cell lysates. These results show that aloesin prevents not only UV-B-induced immune suppression, but also could be a positive pigment-altering agent for cosmetic application. In preclinical study, aloe extract was investigated using phagocytosis and nitroblue tetrazolium chloride (NBT) reduction in adult bronchial asthma, and high molecular-weight materials, such as polysaccharide and glycoprotein fractions, were identified as active ingredients. The neutral polysaccharides, aloemannan and acemannan showed antitumor, antiinflammatory and immunosuppressive activities, and glycoprotein fractions with bradykinindegrading and cell proliferation-stimulating activities were identified from the nondialysate fraction of the gel part of Aloe species. Verectin fractionated from Aloe vera gel was examined biochemically and immunochemically, and verectin antibody was used in the appraisal of commercial Aloe vera gel products. It was reported that aloesin stimulates the proliferation of cultured human hepatoma SK-Hep 1 cells. Thus aloesin, related compounds, and high molecular-weight materials, such as aloemannan and verectin, may act in concert to exert therapeutic properties for wounds, burns and inflammation. The biodisposition of fluoresceinylisothiocyanate (FITC)--labeled aloemannan (FITC-AM) with the homogenate from some organs in mice was demonstrated, and FITC-AM was metabolized to a smaller molecule (MW 3000) by the large intestinal microflora in feces. The modified aloe polysaccharide (MW: 80000) with cellulase under restricted conditions, immunologically stimulated the recovery of UV-B-induced tissue in jury. Thus the modified polysaccharides of aloemannan, together with acemannan (MW: about 600000), are expected to participate in biological activity following oral administration. The effects of tanshinone VI, a diterpenoid isolated from Salvia miltiorrhiza, on the heart are reviewed. First, the effects on the posthypoxic recovery of contractile function of perfused rat hearts were examined. Hypoxia/reoxygenation induced a release of purine nucleosides and bases (ATP metabolites) and resulted in little recovery of contractile force of reoxygenated hearts. Pretreatment of the perfused heart with 42 nM tanshinone VI under hypoxic conditions attenuated the release of ATP metabolites during hypoxia/reoxygenation. Treatment with tanshinone VI enhanced the posthypoxic recovery of myocardial contractility. These results show that tanshinone VI may protect the heart against hypoxia/reoxygenation injury and improve the posthypoxic cardiac function. Second, the effects of tanshinone VI on in vitro myocardial remodeling were examined. Cardiomyocytes and cardiac fibroblasts were isolated from neonatal rat hearts, and simultaneously prepared insulin-like growth factor-1 (IGF-1) induced the hypertrophy of cardiomyocytes. IGF-1 increased the collagen synthesis of cardiac fibroblasts, that is, in vitro fibrosis. The hypertrophy of cardiomyocytes was attenuated in the presence of tanshinone VI in the culture medium. The fibrosis of cardiac fibroblasts was decreased by treatment with tanshinone VI. When tanshinone VI was added to cardiac fibroblast-conditioned medium, the medium-mediated hypertrophy of cardiomyocytes was also attenuated. These results show that tanshinone VI may attenuate in vitro cardiac remodeling. The series of studies has shown that tanshinone VI protects the myocardium against hypoxia/reoxygenation injury and attenuates progression of in vitro myocardial remodeling, suggesting that tanshinone VI is a possible agent for the treatment of cardiac disease with contractile failure.
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PMID:[Anti-inflammatory constituents, aloesin and aloemannan in Aloe species and effects of tanshinon VI in Salvia miltiorrhiza on heart]. 1287 35

The microphthalmia transcription factor (Mitf) activates melanocyte-specific gene expression, is critical for survival and proliferation of melanocytes during development, and has been described as an oncogene in malignant melanoma. SWI/SNF complexes are ATP-dependent chromatin-remodeling enzymes that play a role in many developmental processes. To determine the requirement for SWI/SNF enzymes in melanocyte differentiation, we introduced Mitf into fibroblasts that inducibly express dominant negative versions of the SWI/SNF ATPases, Brahma or Brahma-related gene 1 (BRG1). These dominant negative SWI/SNF components have been shown to inhibit gene activation events that normally require SWI/SNF enzymes. We found that Mitf-mediated activation of a subset of endogenous melanocyte-specific genes required SWI/SNF enzymes but that cell-cycle regulation occurred independently of SWI/SNF function. Activation of tyrosinase-related protein 1, a melanocyte-specific gene, correlated with SWI/SNF-dependent changes in chromatin accessibility at the endogenous locus. Both BRG1 and Mitf could be localized to the tyrosinase-related protein 1 and tyrosinase promoters by chromatin immunoprecipitation, whereas immunofluorescence and immunoprecipitation experiments indicate that Mitf and BRG1 co-localized in the nucleus and physically interacted. Together these results suggest that Mitf can recruit SWI/SNF enzymes to melanocyte-specific promoters for the activation of gene expression via induced changes in chromatin structure at endogenous loci.
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PMID:The microphthalmia-associated transcription factor requires SWI/SNF enzymes to activate melanocyte-specific genes. 1664 30

Cotton plants (Gossypium hirsutum. Linn. var. Sankar 4) were grown at normal and toxic levels of substrate manganese, and the altered metabolism of manganese toxic plants was studied. The tissues of plants exposed to toxic levels of manganese had higher activities of peroxidase and polyphenol oxidase, and the activities of catalase, ascorbic acid oxidase, glutathione oxidase and cytochrome c oxidase were lowered. In addition, the high manganese tissue had lower contents of ATP and glutathione but higher amounts of ascorbic acid. The respiration of the partially expanded leaves and the growing tips of toxic plants were depressed when compared to that of the normal tissues. The metabolic changes of manganese toxicity of cotton are placed in the following order: accumulation of manganese in the leaf tissue; a rise in respiration; stimulation of polyphenol oxidase; the appearance of initial toxicity symptoms; the evolution of ethylene and stimulation of peroxidase; the presence of severe toxicity symptoms; the depression of terminal oxidases and respiration; abscission of the growing tip and proliferation of the stem tissue. The early stimulation of polyphenol oxidase may be used to detect potential manganese toxicity.
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PMID:The manganese toxicity of cotton. 1665 24

Growth inhibition in acid soils due to Al stress affects crop production worldwide. To understand mechanisms in sensitive crops that are affected by Al stress, a proteomic analysis of primary tomato root tissue, grown in Al-amended and non-amended liquid cultures, was performed. DIGE-SDS-MALDI-TOF-TOF analysis of these tissues resulted in the identification of 49 proteins that were differentially accumulated. Dehydroascorbate reductase, glutathione reductase, and catalase enzymes associated with antioxidant activities were induced in Al-treated roots. Induced enzyme proteins associated with detoxification were mitochondrial aldehyde dehydrogenase, catechol oxidase, quinone reductase, and lactoylglutathione lyase. The germin-like (oxalate oxidase) proteins, the malate dehydrogenase, wali7 and heavy-metal associated domain-containing proteins were suppressed. VHA-ATP that encodes for the catalytic subunit A of the vacuolar ATP synthase was induced and two ATPase subunit 1 isoforms were suppressed. Several proteins in the active methyl cycle, including SAMS, quercetin 3-O-methyltransferase and AdoHcyase, were induced by Al stress. Other induced proteins were isovaleryl-CoA dehydrogenase and the GDSL-motif lipase hydrolase family protein. NADPH-dependent flavin reductase and beta-hydroxyacyl-ACP dehydratase were suppressed.
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PMID:Proteome changes induced by aluminium stress in tomato roots. 1982 Mar 57

Semiconductor quantum dots (QDs) are used for the optical analysis of casein kinase (CK2) or the hydrolytic activity of alkaline phosphatase (ALP). Two schemes for the analysis of CK2 by a FRET-based mechanism are described. One approach involves the CK2-catalyzed phosphorylation of a serine-containing peptide (1), linked to CdSe/ZnS QDs, with Atto-590-functionalized ATP. The second analytical method involves the specific association of the Atto-590-functionalized antibody to the phosphorylated product. The hydrolytic activity of ALP is followed by the application of phosphotyrosine (4)-modified CdSe/ZnS QDs in the presence of tyrosinase as a secondary reporter biocatalyst. The hydrolysis of (4) yields the tyrosine units that are oxidized by O(2)/tyrosinase to the respective dopaquinone product. The latter quinone units quench the QDs via an electron transfer route, leading to the optical detection of the ALP activity.
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PMID:Probing protein kinase (CK2) and alkaline phosphatase with CdSe/ZnS quantum dots. 2048 36


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