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)

An anti-cancer peptide was purified from the Mercenaria (Meretrix meretrix Linnaeus) by the method of chromatography on Sephadex G-25 and FPLC, and its molecular weight was determined to be 3147 Da by the way of MALDI-TOF mass spectrum. The effects of this peptide on human gastric gland carcinoma cells (BGC-823) and their cytoskeletal morphology were investigated. The results showed that the peptide could inhibit the proliferation of BGC-823 cells and obviously destroy the skeletal structures of the cells. When the concentration of the peptide reached 4.0 microg/ml, the inhibition percentage of the cell growth was about 60%. The effects of this anticancer peptide on the activities of superoxide dismutase (SOD), alkaline phosphatase (ALP) and tyrosinase were studied. The results showed that the peptide activated ALP and SOD, but inhibit the tyrosinase activity. When the concentration of the peptide reached to 0.5 microg/ml, the relative activities of SOD, ALP and tyrosinase were determined to be 188.5%, 122.0% and 27.5%, respectively.
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PMID:Inhibitory effects of anticancer peptide from Mercenaria on the BGC-823 cells and several enzymes. 1571 Apr 11

In vivo effect of standard and prospective chemosterilants on some enzymes is reported. Colorimetric and histochemical findings indicate that alkaline phosphatase is inhibited by shikonin, hempa, tepa and shikonin angelate. Cholinesterase is inhibited by all the compounds while diphenol oxidase is not inhibited. These findings have been discussed in the light of the earlier observations.
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PMID:Biochemical and electrophoretical studies of the effect of some chemosterilants on theenzymes of aedes aegypti (L.) larvae. 1641 18

The ellipsometric characterization of a layer-by-layer electrostatically self-assembled multilayer of polyphenol oxidase and alkaline phosphatase with the polycation poly(dimethyldiallylammonium chloride) built on an immunologic layer formed by immunoglobulin G (IgG) and glucose oxidase-conjugated anti-IgG (IgG-GOD) on glassy carbon is reported. The step-by-step evolution of the psi-Delta ellipsometric angles was followed during film growth. Two optical models, named the three-layer film model and reorganization film model, were employed and found suitable for ellipsometric data interpretation. A comparative analysis of film optical properties, film thickness, and ellipsometric mass assessed from both models is also presented.
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PMID:Unraveling the spatial distribution of immunoglobulins, enzymes, and polyelectrolytes within layer-by-layer self-assembled multilayers. Ellipsometric studies. 1701 37

The similar dimensions of biomolecules such as enzymes, antibodies or DNA, and metallic or semiconductor nanoparticles (NPs) enable the synthesis of biomolecule-NP hybrid systems where the unique electronic, photonic and catalytic properties of NPs are combined with the specific recognition and biocatalytic properties of biomolecules. The unique functions of biomolecule-NP hybrid systems are discussed with several examples: (i) the electrical contacting of redox enzymes with electrodes is the basis for the development of enzymatic electrodes for amperometric biosensors or biofuel cell elements. The reconstitution of the apo-glucose oxidase or apo-glucose dehydrogenase on flavin adenine dinucleotide (FAD)-functionalized Au NPs (1.4 nm) associated with electrodes, or on pyrroloquinoline quinone (PQQ)-functionalized Au NPs (1.4 nm) associated with electrodes, respectively, yields electrically contacted enzyme electrodes. The aligned, reconstituted enzymes on the electrode surfaces reveal effective electrical contacting, and the glucose oxidase and glucose dehydrogenase reveal turnover rates of 5000 and 11,800 s(-1), respectively. (ii) The photoexcitation of semiconductor nanoparticles yields fluorescence with a wavelength controlled by the size of the NPs. The fluorescence functions of semiconductor NPs are used to develop a fluorescence resonance energy transfer (FRET) assay for nucleic acids, and specifically, for analyzing telomerase activity in cancer cells. CdSe-ZnS NPs are functionalized by a primer recognized by telomerase, and this is elongated by telomerase extracted from HeLa cancer cells in the presence of dNTPs and Texas-red-functionalized dUTP. The dye integrated into the telomers allows the FRET process that is intensified as telomerization proceeds. Also, the photoexcited electron-hole pair generated in semiconductor NPs is used to generate photocurrents in a CdS-DNA hybrid system associated with an electrode. A redox-active intercalator, methylene blue, was incorporated into a CdS-duplex DNA monolayer associated with a Au electrode, and this facilitated the electron transfer between the electrode and the CdS NPs. The direction of the photocurrent was controlled by the oxidation state of the intercalator. (iii) Biocatalysts grow metallic NPs, and the absorbance of the NPs provides a means to assay the biocatalytic transformations. This is exemplified with the glucose oxidase-induced growth of Au NPs and with the tyrosinase-stimulated growth of Au NPs, in the presence of glucose or tyrosine, respectively. The biocatalytic growth of the metallic NPs is used to grow nanowires on surfaces. Glucose oxidase or alkaline phosphatase functionalized with Au NPs (1.4 nm) acted as 'biocatalytic inks' for the synthesis of metallic nanowires. The deposition of the Au NP-modified glucose oxidase, or the Au NP-modified alkaline phosphatase on Si surfaces by dip-pen nanolithography led to biocatalytic templates, that after interaction with glucose/AuCl4- or p-aminophenolphosphate/Ag+, allowed the synthesis of Au nanowires or Ag nanowires, respectively.
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PMID:Integrated nanoparticle-biomolecule systems for biosensing and bioelectronics. 1707 Oct 70

A novel progesterone immunosensor using a colloidal gold-graphite-Teflon-tyrosinase composite biosensor as amperometric transducer is reported. A sequential competitive configuration between the analyte and progesterone labelled with alkaline phosphatase (AP) was used. Phenyl phosphate was employed as the AP-substrate and the enzyme reaction product, phenol, was oxidized by tyrosinase to o-quinone, which is subsequently reduced at -0.1 V at the biocomposite electrode. Variables such as the concentration of phenyl phosphate, the amount of antibody attached to the electrode surface, immersion time in a 2% BSA solution, working pH and incubation times in progesterone and AP conjugate were optimized. A linear calibration graph for progesterone was obtained between 0 and 40 ng mL(-1) with a slope value of -82.3 nA ng(-1) mL, and a detection limit of 0.43 ng mL(-1). The time needed to reach the steady-state current from the addition of phenyl phosphate was 30-40 s. These analytical characteristics improve substantially those reported for other progesterone immunosensors. A lifetime of 14 days with no need to apply any regeneration procedure was also achieved. The usefulness of the immunosensor was evaluated by determining progesterone in milk samples spiked with the analyte at 5.0 and 1.5 ng mL(-1) concentration levels. Following a very simple procedure, involving only sample dilution, mean recoveries (n=7) of 98+/-3% and 99+/-3%, respectively, were obtained.
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PMID:Nanostructured progesterone immunosensor using a tyrosinase-colloidal gold-graphite-Teflon biosensor as amperometric transducer. 1761 44

An amperometric immunosensor for the quantification of Staphylococcus aureus based on the coimmobilization of rabbit immunoglobulin G (RbIgG) and tyrosinase on a mercaptopropionic acid self-assembled monolayer modified gold electrode is reported. A competitive mode in which protein-A-bearing S. aureus cells and antiRbIgG labeled with alkaline phosphatase (AP) compete for the binding sites of immobilized RbIgG was used. Monitoring of the affinity reaction was carried out by the amperometric detection at -0.15 V of phenol generated in the enzyme reaction with AP, at the tyrosinase-modified electrode through the electrochemical reduction of the o-quinone formed. Optimization of the working variables, such as the immunosensor composition and incubation times, the applied potential, the working pH and the concentration of phenyl phosphate used as the AP substrate, was carried out. Under the optimized conditions, both the repeatability of the measurements and the reproducibility of the responses obtained with different immunosensors yielded relative standard deviation values for the steady-state current lower than 10%. The immunosensor showed a dynamic range from 4.4x10(5) to 1.8x10(7) S. aureus cells mL(-1), with a detection limit of 1.7x10(5) cells mL(-1). The limit of detection was remarkably improved by subjecting S. aureus cells to wall lysis by heat treatment. The value obtained was 2.3x10(3) cells mL(-1), which is adequate for the monitoring of S. aureus contamination levels in some foodstuffs. As an application, milk samples spiked with bacteria at the 4.8x10(3) cells mL(-1) level were analyzed.
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PMID:Immunosensor for the determination of Staphylococcus aureus using a tyrosinase-mercaptopropionic acid modified electrode as an amperometric transducer. 1818 27

A bienzyme biosensor based on tyrosinase and horse-radish peroxidase is described in a flow injection analysis and cyclic voltammetry for measurement of phenol. Tyrosinase and horse-radish peroxidase were immobilized on the surface of a glassy carbon electrode by bovine serum albumin and glutaric dialdehyde. Phenol was oxidized by tyrosinase and horse-radish peroxidase via catechol to o-quinone in the presence of oxygen and hydrogen peroxide. The o-quinone was reduced to produce catechol (the substrate recycling) on the electrode surface. The enhanced sensitivity of the bienzyme electrode to phenol was observed in the flow injection system comparing with tyrosinase and horse-radish peroxidase monoenzyme electrodes. The mechanisms for enhanced amperometric response to phenol of bienzyme electrode were discussed. The biosensor was used to detect alkaline phosphatase (ALP). A detection limit of 1.4x10(-15) M ALP (140 zmol/100 mul) was obtained after 1 h incubation with phenyl phosphate.
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PMID:Detection of zeptomolar concentrations of alkaline phosphatase based on a tyrosinase and horse-radish peroxidase bienzyme biosensor. 1896 31

With the continuing increase in human activities, ecologists are increasingly interested in understanding the effects of acid rain on litter decomposition. Two dominant litters were chosen from Zijin Mountain in China: Quercus acutissima from a broad-leaved forest and Pinus massoniana from a coniferous forest. The litters were incubated in microcosms and treated with simulated acid rain (gradient pH levels). During a six-month incubation, changes in chemical composition (i.e., lignin, total carbohydrate, and nitrogen), litter mass losses, soil pH values, and activities of degradative enzymes were determined. Results showed that litter mass losses were depressed after exposure to acid rain and the effects of acid rain on the litter decomposition rates of needles were higher than on those of leaves. Results also revealed that simulated acid rain restrained the activities of cellulase, invertase, nitrate reductase, acid phosphatase, alkaline phosphatase, polyphenol oxidase, and urease, while it enhanced the activities of catalase in most cases during the six-month decomposition process. Catalase and polyphenol oxidase were primarily responsible for litter decomposition in the broad-leaved forest, while invertase, nitrate reductase, and urease were primarily responsible for litter decomposition in the coniferous forest. The results suggest acid rain-restrained litter decomposition may be due to the depressed enzymatic activities. According to the results of this study, soil carbon in subtropical forests would accumulate as a long-term consequence of continued acid rain. This may presumably alter the balance of ecosystem carbon flux, nutrient cycling, and humus formation, which may, in turn, have multiple effects on forest ecosystems.
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PMID:Effect of simulated acid rain on the litter decomposition of Quercus acutissima and Pinus massoniana in forest soil microcosms and the relationship with soil enzyme activities. 2038 10

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

Pesticides are released intentionally into the environment and, through various processes, contaminate the environment. Three of the main classes of pesticides that pose a serious problem are organochlorines, organophosphates and carbamates. While pesticides are associated with many health effects, there is a lack of monitoring data on these contaminants. Traditional chromatographic methods are effective for the analysis of pesticides in the environment, but have limitations and prevent adequate monitoring. Enzymatic methods have been promoted for many years as an alternative method of detection of these pesticides. The main enzymes that have been utilised in this regard have been acetylcholinesterase, butyrylcholinesterase, alkaline phosphatase, organophosphorus hydrolase and tyrosinase. The enzymatic methods are based on the activation or inhibition of the enzyme by a pesticide which is proportional to the concentration of the pesticide. Research on enzymatic methods of detection, as well as some of the problems and challenges associated with these methods, is extensively discussed in this review. These methods can serve as a tool for screening large samples which can be followed up with the more traditional chromatographic methods of analysis.
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PMID:Review on the use of enzymes for the detection of organochlorine, organophosphate and carbamate pesticides in the environment. 2105 90


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