| direct electrochemistry and electrocatalysis based on a film of horseradish peroxidase intercalated into ni-al layered double hydroxide nanosheets. | positively charged ni-al layered double hydroxide nanosheets (ni-al ldhns) have been used for the first time as matrices for immobilization of horseradish peroxidase (hrp) in order to fabricate enzyme electrodes for the purpose of studying direct electron transfer between the redox centers of proteins and underlying electrodes. x-ray diffraction (xrd) and high-resolution transmission electron microscopy (hrtem) revealed that the hrp-ni-al ldhns film had an ordered structure and that hrp was inte ... | 2008 | 18501581 |
| inhibition of myeloperoxidase-mediated protein nitration by tempol: kinetics, mechanism, and implications. | despite the therapeutic potential of tempol (4-hydroxy-2,2,6,6-tetra-methyl-1-piperidinyloxy) and related nitroxides as antioxidants, their effects on peroxidase-mediated protein tyrosine nitration remain unexplored. this posttranslational protein modification is a biomarker of nitric oxide-derived oxidants, and, relevantly, it parallels tissue injury in animal models of inflammation and is attenuated by tempol treatment. here, we examine tempol effects on ribonuclease (rnase) nitration mediated ... | 2008 | 18499804 |
| highly sensitive biosensor based on bionanomultilayer with water-soluble multiwall carbon nanotubes for determination of phenolics. | a highly sensitive biosensor was developed based on bionanomultilyer with water-soluble carbon nanotubes (cnts). the water-soluble poly(allylamine hydrochloride)-wrapped multiwall carbon nanotubes (pah-mwnts) can be obtained for the first time relying on the function of barbiturates, which provides a useful avenue for cnt application in material science and biosensor technology. based on this, the pah-mwnts/horseradish peroxidase (hrp) bionanomultilayer was prepared via layer-by-layer (lbl) asse ... | 2008 | 18499431 |
| [effect of herbicide tralkoxydim and 2-acylcyclohexane-1,3-diones on peroxidase activity]. | effect of 2-acylcyclohexane-1,3-dione derivatives (tralkoxydim and its diketone precursors) on peroxidase-catalyzed oxidation of 3,3',5,5'-tetramethylbenzidine (tmb), o-phenylenediamine (pda), and the phenol-4-aminoantipyrine (4-aap) couple has been studied. this effect varies from horseradish peroxidase (hrp) inactivation to activation in the reactions of peroxidation oftmb, pda, and, to a lesser extent, the phenol-4-aap couple. the diketone-mediated hrp activation depends strongly on ph, prese ... | 2015 | 18491593 |
| electrochemical detection of low-copy number salivary rna based on specific signal amplification with a hairpin probe. | we developed a technique for electrochemical detection of salivary mrna employing a hairpin probe (hp). steric hindrance (sh) suppresses unspecific signal and generates a signal-on amplification process for target detection. the stem-loop configuration brings the reporter end of the probe into close proximity with the surface and makes it unavailable for binding with the mediator. target binding opens the hairpin structure of the probe, and the mediator can then bind to the accessible reporter. ... | 2008 | 18487624 |
| consensus mutagenesis reveals that non-helical regions influence thermal stability of horseradish peroxidase. | the enzyme horseradish peroxidase has many uses in biotechnology but a stabilized derivative would have even wider applicability. to enhance thermal stability, we applied consensus mutagenesis (used successfully with other proteins) to recombinant horseradish peroxidase and generated five single-site mutants. unexpectedly, these mutations had greater effects on steady-state kinetics than on thermal stability. only two mutants (t102a, t110v) marginally exceeded the wild type's thermal stability ( ... | 2008 | 18486625 |
| direct electrochemistry of horseradish peroxidase on tio(2) nanotube arrays via seeded-growth synthesis. | horseradish peroxidase (hrp) was successfully immobilized on vertically oriented tio(2) nanotube arrays (ntas), which was prepared by a seeded-growth mechanism. the nanotubular structure of tio(2) was characterized by scanning electron microscope (sem). after encapsulated hrp on tio(2) nanotube arrays, the direct electron transfer of hrp was observed. owing to the redox reaction of electroactive center of hrp, the hrp/tio(2) ntas modified electrode exhibited a pair of quasi-reversible peaks with ... | 2008 | 18485691 |
| electron transfer activation of chromopyrrolic acid by cytochrome p450 en route to the formation of an antitumor indolocarbazole derivative: theory supports experiment. | qm/mm calculations support experiment and show that stap is a p450 that functions like a peroxidase: its active species is the one-electron-reduced cpd ii species with a radical on cpa, by analogy to cytochrome c peroxidase (ccp), and its reaction with the substrate proceeds by overall proton-coupled electron transfer (pcet), in analogy to the corresponding mechanism in horseradish peroxidase (hrp). the electron transfer is enabled by his250, the presence of carboxylate groups in cpa, and by the ... | 2008 | 18481854 |
| determination of glucose using a coupled-enzymatic reaction with new fluoride selective optical sensing polymeric film coated in microtiter plate wells. | the determination of glucose in beverages is demonstrated using newly developed fluoride selective optical sensing polymeric film that contains aluminum (iii) octaethylporphyrin (al[oep]) ionophore and the chromoionophore eth7075 cast at the bottom of wells of a 96-well polypropylene microtiter plate. the method uses a dual enzymatic reaction involving glucose oxidase enzyme (god) and horseradish peroxidase (hrp), along with an organofluoro-substrate (4-fluorophenol) as the source of fluoride io ... | 2007 | 18480896 |
| a third-generation hydrogen peroxide biosensor based on horseradish peroxidase immobilized in a tetrathiafulvalene-tetracyanoquinodimethane/multiwalled carbon nanotubes film. | a new third-generation biosensor for h(2)o(2) assay was developed on the basis of the immobilization of horseradish peroxidase (hrp) in a nanocomposite film of tetrathiafulvalene-tetracyanoquinodimethane (ttf-tcnq)/multiwalled carbon nanotubes (mwcnts) modified gold electrode. the prepared hrp/ttf-tcnq/mwcnts/au electrode was used for the bioelectrocatalytic reduction of h(2)o(2), with a linear range from 0.005 to 1.05 mm and a detection limit of 0.5 microm for amperometric sensing of h(2)o(2). ... | 2008 | 18479905 |
| protein detection enhanced by 3dna dendrimer signal amplification. | dna dendrimers, conjugated with both anti-biotin antibodies and up to 350 labeling entities, were designed and adapted to protein microarray and enzyme-linked immunosorbent assay (elisa) to improve the limits of protein detection with no additional steps or equipment. application of conjugated dendrimers to standard elisa cytokine detection resulted in up to threefold improvement of the limits of detection with no significant increase in the inter- and intra-assay coefficient of variation (cv) c ... | 2008 | 18476836 |
| myoepithelial differentiation in breast carcinoma. | the aim of presenting this work is to describe a matrix producing carcinoma with anaplastic myoepithelial cell foci, with the coexistence of in situ myoepithelial carcinoma which originated from a sclerosing adenosis. | 2008 | 18468346 |
| removal of linear and branched alkylphenols from aqueous solutions with horseradish peroxidase. | alkylphenols were effectively treated with horseradish peroxidase at ph 7.0 and 30 degrees c in the presence of h(2)o(2) and poly(ethylene glycol) irrespective of the relative position or isomeric form of the alkyl chains. water-insoluble oligomer precipitates were readily filtered out after enzymatic treatment, and transparent and colorless solutions were obtained for all p- and m-alkylphenols used. | 2008 | 18460791 |
| spectroscopic studies of catanionic reverse microemulsion: correlation with the superactivity of horseradish peroxidase enzyme in a restricted environment. | catanionic microemulsions formed by dodecyltrimethylammonium bromide (dtab), sodium dodecyl sulfate (sds), n-hexanol, dodecane, and citrate buffer have been characterized by using dynamic light scattering (dls) and spectroscopic studies. while the dls measurements provide information about the hydrodynamic diameters of the microemulsion droplets formed upon variation of the constituents, steady-state and time-resolved fluorescence emission experiments probe the polarity and the dynamics of the t ... | 2008 | 18457442 |
| immobilization of horseradish peroxidase on nonwoven polyester fabric coated with chitosan. | the immobilization of horseradish peroxidase (hrp) on composite membrane has been investigated. this membrane was prepared by coating nonwoven polyester fabric with chitosan glutamate in the presence of glutraldehyde as a crosslinking agent. the physicochemical properties of soluble and immobilized hrp were evaluated. the soluble hrp lost 90% of its activity after 4 weeks of storage at 4 degrees c, whereas the immobilized enzyme retained 85% of its original activity at the same time. a reusabili ... | 2008 | 18456948 |
| one-step construction of biosensor based on chitosan-ionic liquid-horseradish peroxidase biocomposite formed by electrodeposition. | a simple and controllable electrodeposition approach was established for one-step construction of hydrogen peroxide (h(2)o(2)) biosensors by in situ formation of chitosan-ionic liquid-horseradish peroxidase (cs-il-hrp) biocomposite film on electrode surface. a highly porous surface with orderly three-dimensional network was revealed by scanning electron microscopy (sem) investigation. the biocomposite provided improved conductivity and biocompatible microenvironment. the developed biosensor exhi ... | 2008 | 18456489 |
| a new chemiluminescence paradox: selective inhibition of isoluminol-amplified activity in phagocytes by peptides from annexin ai. | chemiluminescence systems enhanced by either isoluminol or luminol in combination with a peroxidase are sensitive methods for the detection of reactive oxygen species (ros) generated by phagocyte nadph oxidase. the two amplifying substrates are structurally very similar, differing only in the position of the amino group in the aromatic ring of the molecules. this difference renders isoluminol a less lipophilic molecule that is less permeable to biological membranes. the use of isoluminol is cons ... | 2013 | 18452130 |
| thermostability, solvent tolerance, catalytic activity and conformation of cofactor modified horseradish peroxidase. | artificial prosthetic groups, hemind1 and hemind2, were designed and synthesized, which contain one benzene ring and one carboxylic group or two carboxylic groups at the terminal of each propionate side chain of hemin, respectively. hemind1 and hemind2 were reconstituted with apo-hrp successfully to produce the two novel hrps, rhrp1 and rhrp2, respectively. the thermal and solvent tolerances of native and reconstituted hrps were compared. the cofactor modification increased the thermostability b ... | 2008 | 18439429 |
| a chemiluminescent immunosensor based on antibody immobilized carboxylic resin beads coupled with micro-bubble accelerated immunoreaction for fast flow-injection immunoassay. | a novel immunoaffinity column used as an immunosensor for flow-injection chemiluminescent (cl) immunoassay was prepared by immobilizing antibody on carboxylic resin beads. the immunosensor could fast recognize and trap the immunocomplex of horseradish peroxidase (hrp)-labeled antibody and antigen, which was firstly formed with a micro-bubble accelerated pre-incubation process, to produce a sandwich immunocomplex. the hrp introduced in the immunoaffinity column could catalyze the cl reaction to p ... | 2008 | 18430562 |
| integrated biosensor systems for ethanol analysis. | different integrated systems with a bi-enzymatic biosensor, working with two different methods for ethanol detection--flow injection analysis (fia) or sequential injection analysis (sia)--were developed and applied for ethanol extracted from gasohol mixtures, as well as for samples of alcoholic beverages and fermentation medium. a detection range of 0.05-1.5 g ethanol/l, with a correlation coefficient of 0.9909, has been reached when using fia system, working with only one microreactor packed wi ... | 2008 | 18421593 |
| single-cell identification in microbial communities by improved fluorescence in situ hybridization techniques. | the ribosomal-rna (rrna) approach to microbial evolution and ecology has become an integral part of environmental microbiology. based on the patchy conservation of rrna, oligonucleotide probes can be designed with specificities that range from the species level to the level of phyla or even domains. when these probes are labelled with fluorescent dyes or the enzyme horseradish peroxidase, they can be used to identify single microbial cells directly by fluorescence in situ hybridization. in this ... | 2008 | 18414500 |
| nanoelectrode ensembles as recognition platform for electrochemical immunosensors. | in this study we demonstrate the possibility to prepare highly sensitive nanostructured electrochemical immunosensors by immobilizing biorecognition elements on nanoelectrode ensembles (nees) prepared in track-etch polycarbonate membranes. the gold nanodisk electrodes act as electrochemical transducers while the surrounding polycarbonate binds the antibody-based biorecognition layer. the interaction between target protein and antibody is detected by suitable secondary antibodies labelled with a ... | 2008 | 18407487 |
| disposable biosensor and biocatalysis of horseradish peroxidase based on sodium alginate film and room temperature ionic liquid. | composite material based on room temperature ionic liquid (rtil) n-butylpyridinium hexafluorophosphate (bppf(6)), sodium alginate (sa), and graphite was used to construct a novel horseradish peroxidase (hrp) biosensor for the determination of h(2)o(2). the morphology of the as-prepared biosensor was characterized by scanning electron microscopy (sem). cyclic voltammetry (cv) and electrochemical impedance spectroscopy (eis) were used to characterize the process of the performance of the biosensor ... | 2008 | 18406831 |
| direct determination of horseradish peroxidase encapsulated in liposomes by using luminol chemiluminescence. | horseradish peroxidase (hrp) encapsulated in liposomes was directly detected by using luminol chemiluminescence (cl) with h2o2 without lysis of liposomes. at a low concentration of h2o2, the initial rate of hrp-catalyzed luminol cl in liposomes was slower than that of hrp-catalyzed luminol cl in a lipid-free bulk solution. the decrease in the initial rate of the cl reaction in liposomes was due to the membrane permeation of luminol and h2o2. at a high concentration of h2o2, the initial rate of t ... | 2008 | 18403838 |
| high catalytic activities of artificial peroxidases based on supramolecular hydrogels that contain heme models. | composed of a supramolecular hydrogel and a heme model compound, a new type of artificial peroxidase shows high catalytic activity in organic media. the activity of this new type of artificial enzyme is significantly higher than that of the heme model compounds alone. changes in the distal substituents above the coordinated-metal centers of the model compounds directly modulate catalytic activity. this supramolecular-hydrogel-based artificial enzyme is most active in toluene, reaching about 90% ... | 2008 | 18399529 |
| chemiluminescent detection systems of horseradish peroxidase employing nucleophilic acylation catalysts. | the light output of the peroxidase-catalyzed luminol chemiluminescent oxidation reaction can be greatly increased by incorporating different enhancers. such an increase is attributed to the preferential oxidation of the enhancer by peroxidase intermediates and the rapid formation of enhancer radicals that, in turn, quickly oxidize luminol to its radical anion. these enhancers, which include substituted phenols, substituted boronic acids, indophenols, and n-alkyl phenothiazines, behave as electro ... | 2008 | 18394418 |
| optical biosensor based on hollow integrated waveguides. | the first absorbance biosensor based on pure silicon hollow integrated waveguides is presented in this work. with the use of horseradish peroxidase (hrp) as a model recognition element, an enzymatic sensor for the measurement of hydrogen peroxide was fabricated, numerically simulated, and experimentally characterized. waveguides with widths ranging from 50 to 80 microm, having a depth of 50 microm and lengths up to 5 mm were easily fabricated by just one photolithographic step. these were furthe ... | 2008 | 18393473 |
| enzymatic in-capillary derivatization for glucose determination by electrophoresis with spectrophotometric detection. | the following paper compares several procedures of in-capillary bienzymatic derivatization with regard to glucose determination with the use of glucose oxidase and horseradish peroxidase. the procedures discussed below include continuous contact in the capillary, plug-plug injection, and sequential injection with incubation in the capillary inlet. the reaction of hydrogen peroxide catalyzed by peroxidase was performed using two different substrates. the best results were achieved for nicotinamid ... | 2008 | 18383014 |
| gel-based immunoassay for non-instrumental detection of pyrene in water samples. | a new qualitative immunologically based tube test for non-instrumental detection of pyrene (pyr) in water samples was developed. the method combines the pre-concentration of analyte by immunoextraction and its detection by immunoassay using sepharose 4b-immobilized igg-fraction of a polyclonal anti-pyr antiserum (immunoaffinity gel) and 1-pyrenebutyric acid-horseradish peroxidase conjugate (pyr-ba-hrp). the immunoaffinity gel was placed in a standard 1-ml spe column through which a 10-ml aliquot ... | 2008 | 18371915 |
| amperometric sensor for hydrogen peroxide based on electric wire composed of horseradish peroxidase and toluidine blue-multiwalled carbon nanotubes nanocomposite. | a kind of nanocomposites with good dispersion in water was prepared through noncovalent adsorption of toluidine blue (tb) on multiwalled carbon nanotubes (mwcnt) for electric communication between horseradish peroxidase (hrp) and electrode. the nanocomposites could be conveniently cast on electrode surface. with the aid of chitosan, hrp was then immobilized on the nanostructure to form a reagentless amperometric sensor for hydrogen peroxide. uv-vis spectroscopy and electrochemical impedance spec ... | 2008 | 18371735 |
| femtomol spr detection of dna-pna hybridization with the assistance of dna-guided polyaniline deposition. | the inability of surface plasmon resonance (spr) spectroscopy to detect extremely small refractive index changes has hindered its applications in ultrasensitive dna analysis. in this study we report a signal amplification strategy that uses dna-templated polyaniline deposition, suitable for dna hybridization analysis with charge neutral peptide nucleic acid (pna) being probes. under acidic conditions, protonated aniline monomers are adsorbed on dna backbones through electrostatic interaction. th ... | 2008 | 18359218 |
| quantum dots-bienzyme hybrid system for the sensitive determination of glucose. | in this paper, we attempt to develop a sensitive detection method for glucose with the combination of the unique optical property of quantum dots and the specificity of enzymatic reactions. with glucose and hydroquinone as substrates, benzoquinone that intensively quenches the photoluminescence of quantum dots can be produced via the catalysis of bienzyme (glucose oxidase and horseradish peroxidase) system. a relatively low detection limit of 1.0x10(-8)mol/l can be achieved. two linear ranges fr ... | 2008 | 18356038 |
| functional and developmental analysis of the blood-brain barrier in zebrafish. | the blood-brain barrier (bbb) is essential for maintaining brain homeostasis and protecting the brain from toxic substances. breakdown of this barrier results in severe brain pathologies, whereas impermeability of the bbb is a major obstacle for drug delivery to the brain. despite its importance, our understanding of the maturation and modulation of the bbb is limited. zebrafish (danio rerio) has emerged as a useful model organism for studying vertebrate development and disease mechanisms, as we ... | 2008 | 18355638 |
| a dnazyme cascade for the amplified detection of pb(2+) ions or l-histidine. | dnazyme cascades activated by pb(2+)- or l-histidine-dependent dnazymes yield the horseradish peroxidase-mimicking catalytic nucleic acids that enable the colorimetric or chemiluminescence detection of pb(2+) or l-histidine. | 2008 | 18354802 |
| rapid detection of picloram in agricultural field samples using a disposable immunomembrane-based electrochemical sensor. | picloram, a widely used chlorinated herbicide, is quite persistent and mobile in soil and water with adverse health and environmental effects. it is essential to establish a rapid and sensitive method for accurate detection of trace picloram in agricultural samples. we employed a disposable, nontoxic, and conductive chitosan/gold nanoparticles composite membrane on electrochemical sensor for the sensitive detection of picloram in several agricultural field samples. a self-synthesized picloram an ... | 2008 | 18351094 |
| fabrication of bienzyme nanobiocomposite electrode using functionalized carbon nanotubes for biosensing applications. | mediated biosensors consisting of an oxidase and peroxidase (pox) have attracted increasing attention because of their wider applicability. this work presents a novel approach to fabricate nanobiocomposite bienzymatic biosensor based on functionalized multiwalled carbon nanotubes (mwnts) with the aim of evaluating their ability as sensing elements in amperometric transducers. electrochemical behavior of the bienzymatic nanobiocomposite biosensor is investigated by faradaic impedance spectroscopy ... | 2008 | 18343650 |
| all vertebrates started out with a glial blood-brain barrier 4-500 million years ago. | all extant vertebrates have a blood-brain barrier (bbb), a specialized layer of cells that controls molecular traffic between blood and brain, and contributes to the regulation (homeostasis) of the brain microenvironment. such homeostasis is critical for the stable function of synapses and neural networks. the barrier is formed by vascular endothelial cells in most groups, but by perivascular glial cells (astrocytes) in elasmobranch fish (sharks, skates, and rays). it has been unclear which is t ... | 2008 | 18338790 |
| dcfh2 interactions with hydroxyl radicals and other oxidants--influence of organic solvents. | the oxidation of 2',7'-dichlorofluorescin (dcfh(2)) is widely used as a measure to detect the generation of reactive oxygen species (ros) and to analyze oxidative stress. other factors beside commonly known radicals may influence the results of such measurements. therefore, the effects of h(2)o(2), kmno(4,) decomposition products of aaph, ethanol and dmso, antioxidants like ascorbic acid, different ferrous ion chelates, and heme-containing proteins like cytochrome c, myoglobin, hemoglobin, and h ... | 2008 | 18337037 |
| bioelectrochemical immunoassay of polychlorinated biphenyl. | a simple, rapid, and highly sensitive bioelectrochemical immunoassay method based on magnetic beads (mbs) and disposable screen-printed electrodes (spe) has been developed to detect polychlorinated biphenyls (pcbs). the principle of this bioassay is based on a direct competitive enzyme-linked immunosorbent assay using pcb-antibody-coated mbs and horseradish peroxidase (hrp)-labeled pcb (hrp-pcb). a magnetic process platform was used to mix and shake the samples during the immunoreactions and to ... | 2008 | 18331854 |
| biomimetic nitration of the linoleic acid metabolite 13-hydroxyoctadecadienoic acid: isolation and spectral characterization of novel chain-rearranged epoxy nitro derivatives. | nitration of unsaturated fatty acids is a (patho)physiologically important pathway of lipid modification induced by nitric oxide-derived species. we report herein on the unexpected chain rearrangement undergone by (13s,9z,11e)-13-hydroxyoctadeca-9,11-dienoic acid (1), a linoleic acid metabolite, when exposed to nitrating agents of biological relevance. at ph 7.4 and at room temperature, reaction of 1 with peroxynitrite (onoo-) as well as fe2+-edta/h2o2/no2- and horseradish peroxidase/h2o2/no2- l ... | 2008 | 18320610 |
| biotinylated nanodiamond: simple and efficient functionalization of detonation diamond. | we have developed a simple and efficient method for the covalent functionalization of detonation nanodiamond. after homogenization of the surface by borane reduction, the surface was modified with (3-aminopropyl)trimethoxysilane. subsequent grafting of biotin yielded covalently biotinylated nanodiamond, which was characterized by ftir spectroscopy, x-ray powder diffractometry, thermogravimetry, and elemental analysis. the activity was tested with horseradish peroxidase-labeled streptavidin. the ... | 2008 | 18312008 |
| enzymatic amplification detection of dna based on "molecular beacon" biosensors. | we described a novel electrochemical dna biosensor based on molecular beacon (mb) probe and enzymatic amplification protocol. the mb modified with a thiol at its 5' end and a biotin at its 3' end was immobilized on the gold electrode through mixed self-assembly process. hybridization events between mb and target dna cause the conformational change of the mb, triggering the attached biotin group on the electrode surface. following the specific interaction between the conformation-triggered biotin ... | 2008 | 18304797 |
| chitosan as a removing agent of beta-lactoglobulin from membrane models. | many chitosan biological activities depend on the interaction with biomembranes, but so far it has not been possible to obtain molecular-level evidence of chitosan action. in this article, we employ langmuir phospholipid monolayers as cell membrane models and show that chitosan is able to remove beta-lactoglobulin (blg) from negatively charged dimyristoyl phosphatidic acid (dmpa) and dipalmitoyl phosphatidyl glycerol (dppg). this was shown with surface pressure isotherms and elasticity and pm-ir ... | 2008 | 18302443 |
| a novel and highly sensitive resonance scattering spectral assay for horseradish peroxidase using cationic surfactant. | a novel and ultrasensitive resonance scattering (rs) spectral assay was proposed for detection of horseradish peroxidase (hrp) activity. it was based on that the hrp strongly catalyze h2o2 oxidation of excess i- to form i3-, the resulting i3- combined with four cationic surfactant (cs), including tetradecyl pyridinium bromide (tpb), cetyltrimethyl ammonium bromide (ctma), cetylpyridinium chloride (cpcm) and tetradecyl dimethylbenzyl ammonium chloride (tdmba) to produce association particles (tpb ... | 2008 | 18302009 |
| oxidase-peroxidase reaction: kinetics of peroxidase-catalysed oxidation of 2-aminophenol. | possible reaction pathways that may lead to horseradish peroxidase inactivation during the aerobic oxidation of 2-aminophenol were investigated using extended kinetic curves. a kinetic model involving the formation of a low-reactive species, compound iii, was proposed and several rate constants were calculated using an optimisation computing program. sensitivity analysis allowed to conclude that both oxidase and peroxidase cycles occur in 2-aminophenol oxidation. | 2008 | 18299896 |
| in vitro metabolism of a model cyclopropylamine to reactive intermediate: insights into trovafloxacin-induced hepatotoxicity. | trovafloxacin (trovan) is a fluoroquinolone antibiotic drug with a long half-life and broad-spectrum activity. since its entry into the market in 1998, trovafloxacin has been associated with numerous cases of hepatotoxicity, which has limited its clinical usefulness. trovafloxacin possesses two substructural elements that have the potential to generate reactive intermediates: a cyclopropylamine moiety and a difluoroanilino system. the results presented here describe the in vitro metabolic activa ... | 2008 | 18298092 |
| preparation and evaluation of microparticles from thiolated polymers via air jet milling. | microparticles were formulated by incorporation of the model protein horseradish peroxidase in (thiolated) chitosan and (thiolated) poly(acrylic acid) via co-precipitation. dried protein/polymer complexes were ground with an air jet mill and resulting particles were evaluated regarding size distribution, shape, zeta potential, drug load, protein activity, release pattern, swelling behaviour and cytotoxicity. the mean particle size distribution was 0.5-12 microm. non-porous microparticles with a ... | 2008 | 18294828 |
| [removal of pentachlorophenol catalyzed by immobilized horseradish peroxidase]. | the removal of pcp using hrp immobilized by fe3o4 sorption-gelatin embedding-cross linkage method as catalyzer was studied. reaction conditions including the reacting time, different buffer systems and ph value, pcp initial concentration, hrp dosage were discussed in detail compared with free hrp. the results indicate that the equilibrium time of pcp removal reaction catalyzed by immobilized hrp is about 30 min, which is as fast as free hrp. the optimal ph for pcp removal by immobilized hrp is b ... | 2007 | 18290430 |
| theoretical modeling of enzyme reactions: the thermodynamics of formation of compound 0 in horseradish peroxidase. | in this paper, by using the perturbed matrix method (pmm) in combination with basic statistical mechanical relations both based on nanosecond time-scale molecular dynamics (md) simulations, we quantitatively address the thermodynamics of compound 0 (cpd 0) formation in horseradish peroxidase (hrp) enzyme. our results, in the same trend of low-temperature experimental data, obtained in cryoenzymology studies indicate that such a reaction can be described essentially as a stepwise spontaneous proc ... | 2008 | 18288829 |
| facile snp detection using bifunctional, cross-linking oligonucleotide probes. | a facile, sensitive method for detecting specific sequences of oligonucleotides was developed. detection of dna sequences with single nucleotide discrimination is achieved by combining the selectivity of hybridization with an efficient cross-linking reaction. readily synthesized bifunctional oligonucleotide probes containing a modified pyrimidine that is capable of forming interstrand cross-links under mild oxidative conditions internally, and biotin at their 5'-termini were used to discriminate ... | 2008 | 18281702 |
| identification of l-plastin autoantibody in plasma of patients with non-hodgkin's lymphoma using a proteomics-based analysis. | the diagnosis of malignant lymphoma (ml) such as non-hodgkin's lymphoma (nhl) and hodgkin's lymphoma (hl) was mainly performed by morphological examination and gene analysis. there are only a few serum/plasma biomarkers such as lactate dehydrogenase and soluble interleukin-2 receptor alpha to diagnose ml. the classifications are various, and therefore the cell surface markers using flow cytometry or lymph node biopsy have been examined. it is difficult, however, to distinguish the two diseases, ... | 2008 | 18275676 |
| activity increase of horseradish peroxidase in the presence of magnetic particles. | | 2008 | 18275197 |
| one of the possible mechanisms for the inhibition effect of tb(iii) on peroxidase activity in horseradish (armoracia rusticana) treated with tb(iii). | one of the possible mechanisms for the inhibition effect of tb(iii) on peroxidase activity in horseradish (armoracia rusticana) treated with tb(iii) was investigated using some biophysical and biochemical methods. firstly, it was found that a large amount of tb(iii) can be distributed on the cell wall, that some tb(iii) can enter into the horseradish cell, indicating that peroxidase was mainly distributed on cell wall, and thus that tb(iii) would interact with horseradish peroxidase (hrp) in the ... | 2008 | 18274791 |
| utilizing a cdte quantum dots-enzyme hybrid system for the determination of both phenolic compounds and hydrogen peroxide. | in this paper, we attempt to construct a simple and sensitive detection method for both phenolic compounds and hydrogen peroxide, with the successful combination of the unique property of quantum dots and the specificity of enzymatic reactions. in the presence of h2o2 and horseradish peroxidase, phenolic compounds can quench quantum dots' photoluminescence efficiently, and the extent of quenching is severalfold to more than 100-fold increase. quinone intermediates produced from the enzymatic cat ... | 2008 | 18271509 |
| a comparative study of free and immobilized soybean and horseradish peroxidases for 4-chlorophenol removal: protective effects of immobilization. | horseradish peroxidase (hrp) and soybean peroxidase (sbp) were covalently immobilized onto aldehyde glass through their amine groups. the activity yield and the protein content for the immobilized sbp were higher than for the immobilized hrp. when free and immobilized peroxidases were tested for their ability to remove 4-chlorophenol from aqueous solutions, the removal percentages were higher with immobilized hrp than with free hrp, whereas immobilized sbp needs more enzyme to reach the same con ... | 2008 | 18270748 |
| a sensitive chemiluminescence method for the determination of h2o2 in exhaled breath condensate. | in this paper, a novel flow injection chemiluminescence (fi-cl) method is proposed for the determination of picomolar l(-1) levels of hydrogen peroxide (h(2)o(2)) in exhaled breath condensate (ebc). this method is based on the oxidation of a low concentration of luminol (10(-7) m) by h(2)o(2) at a low concentration level (< 10(-8) m) in an alkaline medium catalyzed by a complex, k(5)[cu(hio(6))(2)] (dpc), which is not interfered by other metal ions or horseradish peroxidase (hrp). under the opti ... | 2008 | 18270409 |
| dna-directed synthesis of aniline and 4-aminobiphenyl oligomers: programmed transfer of sequence information to a conjoined polymer nanowire. | a new class of materials was prepared from aniline-containing oligomers that are covalently linked to the nucleobases of duplex dna. oligomers composed of repeating aniline (pani) or 4-aminobiphenyl (pab) units having the properties of conducting polymers conjoined to the dna were prepared by the reaction of horseradish peroxidase and h2o2 with dna having the appropriate monomers aligned within the major groove. these oligomers exhibit the spectral and chemical properties typical of para-linked ... | 2008 | 18266359 |
| in situ hybridization and detection using nonisotopic probes. | nonisotopic in situ hybridization can be used to determine the cellular location and relative levels of expression for specific transcripts within cells and tissues. rna in specimen preparations is hybridized with a biotin- or digoxigenin-labeled probe, which is generally detected by fluorescence or enzymatic methods. fluorescence in situ hybridization (fish), probably the most widely used method, is described here, along with amplification of weak fish signals. nonisotopic probes can also be de ... | 2007 | 18265392 |
| immunoblotting and immunodetection. | immunoblotting (western blotting) is used to identify specific antigens recognized by polyclonal or monoclonal antibodies. this unit provides protocols for all steps starting with solubilization of the protein samples, usually with sds and reducing agents. following solubilization, the material is separated by sds-page and the antigens are electrophoretically transferred to a membrane, a process that can be monitored by reversible staining or ponceau s staining. the transferred proteins are boun ... | 2004 | 18265338 |
| labeling and colorimetric detection of nonisotopic probes. | although a number of different nonisotopic labels have been described in the literature, biotin and digoxigenin are used most frequently and are commercially available. either label can be easily incorporated into dna probes and be detected colorimetrically; a number of fluorochromes, as well as alkaline phosphatase and horseradish peroxidase (which produce colored precipitates) are available directly conjugated to anti-digoxigenin antibodies and to avidin. chemiluminescent detection methods and ... | 2001 | 18265226 |
| lectin analysis of proteins blotted onto filters. | lectins are proteins that bind with great specificity to certain carbohydrate structures. plant lectins are widely used for investigations of carbohydrate structure and for fractionation and purification of individual oligosaccharides and glycopeptides. this unit describes the use of lectins as sensitive indicators for the presence of certain carbohydrate structures linked to proteins blotted onto filters. a tagged lectin is incubated with a blot containing the target protein and binding of the ... | 2001 | 18265163 |
| conjugation of enzymes to antibodies. | conjugation of enzymes to antibodies involves the formation of a stable, covalent linkage between an enzyme [e.g., horseradish peroxidase (hrpo), urease, or alkaline phosphatase] and an antigen-specific monoclonal or polyclonal antibody in which neither the antigen-combining site of the antibody nor the active site of the enzyme is functionally altered. this unit describes procedures for cross-linking hrpo, urease or alkaline phosphatase to immunoaffinity-purified monoclonal or polyclonal antibo ... | 2001 | 18265067 |
| a sensitive resonance scattering spectral assay for the determination of trace h2o2 based on the hrp catalytic reaction and nanogold aggregation. | gold nanoparticles in size of 15 nm exhibit a resonance scattering (rs) peak at 580 nm, in ph 6.4 citrate buffer solutions. horseradish peroxidase (hrp) strongly catalyzed the h2o2 oxidation of o-phenylenediamine to form an intergradation of cyclohexa-3, 5-diene-1, 2-diylidenediamine and the product of 2, 3-diaminophenazin. both cause gold nanoparticles aggregations to enhance the rs intensity at 580 nm greatly. under the optimal conditions, the concentration of h2o2 (c) in the range of 0.08-2.2 ... | 2008 | 18259844 |
| asymmetric biomimetic oxidations of phenols: the mechanism of the diastereo- and enantioselective synthesis of thomasidioic acid. | enantiopure chiral amidic derivatives of sinapic acid were oxidised with hydrogen peroxide using horseradish peroxidase (hrp) as the catalyst to give the aryltetraline dilignol thomasidioic acid. trans-diastereoselectivity and enantioselectivity in the formation of thomasidioic acid was observed. computational methods show that the enantioselectivity is controlled by the beta-beta oxidative coupling step, while the diastereoselectivity is controlled by the stability of the reactive conformation ... | 2008 | 18259136 |
| peroxidase-mediated oxidative cross-linking and its potential to modify mechanical properties in water-soluble polysaccharide extracts and cereal grain residues. | analysis of wheat bran and spent grain shows that concentrations of ferulate and diferulates offer considerable scope to modify the cross-linking of feruloylated polysaccharides and hence the mechanical properties of these residues. in solution ferulic acid (fa) can be readily polymerized by horseradish peroxidase, but when esterified to a polysaccharide, the profile of diferulates becomes restricted. this situation also exists in muro and suggests structural constraints may limit the availabili ... | 2008 | 18251503 |
| multiplex fluorescent in situ hybridization in zebrafish embryos using tyramide signal amplification. | one of the strengths of the zebrafish is the ease with which in situ hybridization can be performed to determine spatial and temporal patterns of gene expression in whole embryos. thus far, colorimetric detection methods are mainly used for these analyses. here we describe a fluorescent in situ hybridization (fish) protocol for whole-mount zebrafish embryos using tyramide signal amplification (tsa). an optimal set of reagents was identified that allows for simultaneous localization of gene expre ... | 2005 | 18248170 |
| peroxidase-mediated formation of the fungal polyphenol 3,14'-bihispidinyl. | medicinal fungi, phellinus linteus and inonotus xeranticus, produce a cluster of yellow pigment in their fermentation broth that acts as an important element of biological activity. the pigment is composed of diverse polyphenols with a styrylpyrone moiety, mainly hispidin and its dimers, 3,14'-bihispidinyl, hypholomine b, and 1,1- distrylpyrylethan. although dimeric hispidins were proposed to be biosynthesized from two molecules of monomer via oxidative coupling by ligninolytic enzymes, laccase ... | 2008 | 18239425 |
| suicide-peroxide inactivation of microperoxidase-11: a kinetic study. | the kinetics of microperoxidase-11 (mp-11) in the oxidation reaction of guaiacol (ah) by hydrogen peroxide was studied, taking into account the inactivation of enzyme during reaction by its suicide substrate, h2o2. concentrations of substrates were so selected that: 1) the reaction was first-order in relation to benign substrate, ah and 2) high ratio of suicide substrate to the benign substrate, [h2o2] > [ah]. validation and reliability of the obtained kinetic equations were evaluated in various ... | 2007 | 18237019 |
| the influence of carbohydrate structures present in common allergen sources on specific ige results. | cross-reactive carbohydrate determinants (ccd) are well known interferants in specific ige assays (sige). glyco-epitopes are not restricted to ccd and extracts used to prepare in vitro tests contain many other glycoproteins able to bind glycan-specific ige. the overall amounts of ige-bindable glycan structures in allergen sources are unknown. | 2007 | 18236996 |
| measuring retrograde transport to the trans-golgi network. | the recently described retrograde transport route is a highly selective pathway that allows some internalized molecules to reach the trans-golgi network from early/recycling endosomes, bypassing the recycling route to the plasma membrane and the late endocytic pathway. the non-toxic receptor-binding b-subunit of bacterial shiga toxin has played an important role in the discovery and molecular dissection of membrane trafficking at the early/recycling endosomes-tgn interface. this unit describes s ... | 2006 | 18228477 |
| immunoblotting and immunodetection. | this unit provides protocols for immunoblotting, which is used to identify specific protein sequences separated by electrophoresis and transferred to an appropriate membrane and recognized by a polyclonal or monoclonal antibody. after the proteins are separated on a gel, they are transferred to a membrane by electroblotting or a semidry transfer system. proteins on the membrane can be visualized with the reversible stain ponceau s to assess the completeness of transfer. then the blot is analyzed ... | 2001 | 18228374 |
| ultrasensitive electrochemical immunosensor for clinical immunoassay using thionine-doped magnetic gold nanospheres as labels and horseradish peroxidase as enhancer. | a new signal amplification strategy based on thionine (th)-doped magnetic gold nanospheres as labels and horseradish peroxidase (hrp) as enhancer holds promise to improve the sensitivity and detection limit of the immunoassay for carcinoembryonic antigen (cea), as a model protein. this immunoassay system was fabricated on a carbon fiber microelectrode (cfme) covered with a well-ordered anti-cea/protein a/nanogold architecture. the reverse micelle method was initially used for the preparation of ... | 2008 | 18220412 |
| enzymatic removal of phenol and p-chlorophenol in enzyme reactor: horseradish peroxidase immobilized on magnetic beads. | horseradish peroxidase was immobilized on the magnetic poly(glycidylmethacrylate-co-methylmethacrylate) (poly(gma-mma)), via covalent bonding and used for the treatment of phenolic wastewater in continuous systems. for this purposes, horseradish peroxidase (hrp) was covalently immobilized onto magnetic poly(gma-mma) beds using glutaraldehyde (ga) as a coupling agent. the maximum hrp immobilization capacity of the magnetic poly(gma-mma)-ga beads was 3.35 mg g(-1). the immobilized hrp retained 79% ... | 2008 | 18207637 |
| effect of ibuprofen l-lysinate on bilirubin binding to albumin as measured by saturation index and horseradish peroxidase assays. | to demonstrate, in vitro, the influence of increasing ibuprofen (ibu) concentration on bilirubin-albumin (b-a) binding. | 2008 | 18200021 |
| immobilization of horseradish peroxidase on chitosan/silica sol-gel hybrid membranes for the preparation of hydrogen peroxide biosensor. | a simple and effective strategy for fabrication of hydrogen peroxide (h2o2) biosensor has been developed by entrapping horseradish peroxidase (hrp) in chitosan/silica sol-gel hybrid membranes (cshms) doped with potassium ferricyanide (k3fe(cn)6) and gold nanoparticles (gnps) on platinum electrode surface. the hybrid membranes are prepared by cross-linking chitosan (cs) with 3-aminopropyltriethoxysilane (aptes), while the presence of gnps improved the conductivity of cshms, and the fe(cn)6(3-/4-) ... | 2008 | 18199484 |
| measurement of ambient hydroperoxides using an automated hplc system and various factors which affect variations of their concentrations in korea. | an hplc system was automated for the measurement of gaseous hydroperoxides in the ambient air. in this system, samples collected using a glass coil without a long sampling tube are injected automatically into hplc. the analytical system is based on the post-column derivatization, which is a reaction of hydroperoxides with p-hydroxyphenyl acetic acid to produce a fluorescent dimer in the presence of horseradish peroxidase as an enzyme catalyst. the detection limits of hydrogen peroxide (h(2)o(2)) ... | 2008 | 18181026 |
| oxidations of n-(3-indoleethyl) cyclic aliphatic amines by horseradish peroxidase: the indole ring binds to the enzyme and mediates electron-transfer amine oxidation. | although oxidations of aromatic amines by horseradish peroxidase (hrp) are well-known, typical aliphatic amines are not substrates of hrp. in this study, the reactions of n-benzyl and n-methyl cyclic amines with hrp were found to be slow, but reactions of n-(3-indoleethyl) cyclic amines were 2-3 orders of magnitude faster. analyses of ph-rate profiles revealed a dominant contribution to reaction by the amine-free base forms, the only species found to bind to the enzyme. a metabolic study on a fa ... | 2008 | 18163622 |
| immunohistochemistry on sections of plant tissues using enzyme-coupled avidin-biotin complex. | introductionlike rna, proteins can be localized in situ on tissue sections. in situ localization or immunohistochemistry provides information on the cellular and subcellular distribution of proteins in different tissues. the technique described in this protocol employs a biotinylated secondary antibody in conjunction with a preformed avidin:biotinylated enzyme complex (abc) for immunohistochemistry. it allows for sensitive detection of antigens while avoiding fluorescent secondary antibodies, wh ... | 2008 | 21356776 |
| immunohistochemistry of embryo sections. | introductionthis protocol describes how to localize an antigen in cells and tissues using embryo sections attached to glass slides. the method outlined here uses alkaline-phosphatase-coupled secondary antibody; horseradish-peroxidase-coupled secondary antibody can be used as an alternative. | 2008 | 21356664 |
| parallel analysis of two analytes in solutions or on surfaces by using a bifunctional aptamer: applications for biosensing and logic gate operations. | a bifunctional aptamer that includes two aptamer units for cocaine and adenosine 5'-monophosphate (amp) is blocked by a nucleic acid to form a hybrid structure with two duplex regions. the blocked bifunctional aptamer assembly is used as a functional structure for the simultaneous sensing of cocaine or amp. the blocked bifunctional aptamer is dissociated by either of the two analytes, and the readout of the separation of the sensing structure is accomplished by a colorimetric detection, by a rel ... | 2008 | 18161727 |
| examination of neurons in wild type and mutants of caenorhabditis elegans using antibodies to horseradish peroxidase. | antibodies to horseradish peroxidase (hrp) recognize 27 of 302 neurons and several non-neuronal cells in adult hermaphrodites of the soil nematode caenorhabditis elegans and can be used to label these cells for cytological analysis in whole animals. the antibodies bind to the anterior members, but not to the posterior members of a set of mechanosensory neurons in wild type animals. binding to one of the posterior mechanosensory neurons (pvm) occurs when this neuron migrates to an abnormal anteri ... | 2007 | 18161589 |
| [sample pre-processing for mass spectrometric analysis of glycoprotein structure]. | a novel, simple and fast method based on a quadrupole ion trap (qit) and a time-of-flight mass spectrograph was developed for the glycosylation site and glycan structure analysis of glycoprotein by in-solution digestion and in-gel digestion which did not need to enrich and label the glycopeptide. horseradish peroxidase (hrp) and rnase b were utilised to optimize the conditions of sample pre-processing. the effects of the conditions were investigated separately and the optimal conditions were: he ... | 2007 | 18161309 |
| photolithographic fabrication of poly(ethylene glycol) microstructures for hydrogel-based microreactors and spatially addressed microarrays. | we describe the fabrication of poly(ethylene glycol) diacrylate (peg-da) hydrogel microstructures with a high aspect ratio and the use of hydrogel microstructures containing the enzyme beta-galactosidase (beta-gal) or glucose oxidase (gox)/horseradish peroxidase (hrp) as biosensing components for the simultaneous detection of multiple analytes. the diameters of the hydrogel microstructures were almost the same at the top and at the bottom, indicating that no differential curing occurred through ... | 2007 | 18092467 |
| embryonic development of a peripheral nervous system: nerve tract associated cells and pioneer neurons in the antenna of the grasshopper schistocerca gregaria. | the grasshopper antenna is an articulated appendage associated with the deutocerebral segment of the head. in the early embryo, the meristal annuli of the antenna represent segment borders and are also the site of differentiation of pioneer cells which found the dorsal and ventral peripheral nerve tracts to the brain. we report here on another set of cells which appear earlier than the pioneers during development and are later found arrayed along these tracts at the border of epithelium and lume ... | 2007 | 18089112 |
| embryonic development of the sensory innervation of the antenna of the grasshopper schistocerca gregaria. | the establishment of the sensory nervous system of the antenna of the grasshopper schistocerca gregaria was examined using immunocytochemical methods and in the light of the appendicular and articulated nature of this structure. the former is demonstrated first by the expression pattern of the segment polarity gene engrailed in the head neuromere innervating the antenna, the deutocerebrum. engrailed expression is present in identified deutocerebral neuroblasts and, as elsewhere in the body, is c ... | 2004 | 18089045 |
| morphological and molecular data argue for the labrum being non-apical, articulated, and the appendage of the intercalary segment in the locust. | our analysis of head segmentation in the locust embryo reveals that the labrum is not apical as often interpreted but constitutes the topologically fused appendicular pair of appendages of the third head metamere. using molecular, immunocytochemical and retrograde axonal staining methods we show that this metamere, the intercalary segment, is innervated by the third brain neuromere-the tritocerebrum. evidence for the appendicular nature of the labrum is firstly, the presence of an engrailed stri ... | 2002 | 18088971 |
| regeneration of retinotectal projections after optic tectum removal in adult newts. | when injured, the adult newt possesses the remarkable capability to regenerate tissues and organs with return of function and physiology. one example is the newt eye, in which regeneration can restore normal vision if the retina or lens has been removed. we wanted to examine how the retinotectal projections regenerate after removal of the brain's optic tectum and establish this animal as a model for retinal projection as well as a central nervous system regeneration model. | 2007 | 18079683 |
| effectiveness of phenoxyl radicals generated by peroxidase/h2o2-catalyzed oxidation of caffeate, ferulate, and p-coumarate in cooxidation of ascorbate and nadh. | the rate of ascorbate and nicotinamide adenine dinucleotide plus hydrogen (nadh) cooxidation (i.e., their nonenzymic oxidation by peroxidase/h2o2-generated phenoxyl radicals of three hydroxycinnamates: caffeate, ferulate and p-coumarate) was studied in vitro. the reactions initiated by different sources of peroxidase (ec 1.11.1.7) [isolates from soybean (glycine max l.) seed coat, maize (zea mays l.) root-cell wall, and commercial horseradish peroxidase] were monitored. native electrophoresis of ... | 2008 | 18071845 |
| encapsulation of quercetin and myricetin in cyclodextrins at acidic ph. | the in vitro formation of quercetin- and myricetin-cyclodextrin inclusion complexes in acidic medium has been characterized using the enzymatic system horseradish peroxidase, which oxidizes those flavonols in the presence of h2o2. the presence of cyclodextrins (cds) in the reaction medium inhibited flavonol oxidation due to the complexation of the flavonol in the hydrophobic cavity of cds. this inhibitory effect depends on the complexation constant kc between flavonol and the cd type used. the k ... | 2008 | 18069793 |
| an amperometric hydrogen peroxide biosensor based on immobilization of horseradish peroxidase on an electrode modified with magnetic dextran microspheres. | a new kind of magnetic dextran microsphere (mdms) with uniform shape and narrow diameter distribution has been prepared from magnetic iron nanoparticles and dextran. horseradish peroxidase (hrp) was successfully immobilized on the surface of an mdms-modified glassy-carbon electrode (gce), and the immobilized hrp displayed excellent electrocatalytic activity in the reduction of h(2)o(2) in the presence of the mediator hydroquinone (hq). the effects of experimental variables such as the concentrat ... | 2008 | 18060389 |
| a bienzyme channeling glucose sensor with a wide concentration range based on co-entrapment of enzymes in sba-15 mesopores. | a novel bienzyme-channeling sensor was constructed by entrapping glucose oxidase (god) and horseradish peroxidase (hrp) in the mesopores of well-ordered hexagonal mesoporous silica structures (sba-15). the sba-15 mesoporous materials accelerated the electron transfer between the entrapped hrp and electrode. both hrp and god retained their catalytic activities in the bienzyme-entrapped sba-15 film. in presence of glucose the enzymatic reaction of god-glucose-dissolved oxygen system generated hydr ... | 2008 | 18054830 |
| direct electrochemistry and electrocatalysis of horseradish peroxidase based on clay-chitosan-gold nanoparticle nanocomposite. | gold nanoparticles stabilized by chitosan (aucs) were hybridized with exfoliated clay nanoplates through electrostatic interaction. the resulting clay-chitosan-gold nanoparticle nanocomposite (clay/aucs) was used to modify glassy carbon electrode (gce). hrp, a model peroxidase, was entrapped between the clay/aucs film and another clay layer. uv-vis spectrum suggested hrp retained its native conformation in the modified film. basal plane spacing of clay obtained by x-ray diffraction (xrd) indicat ... | 2008 | 18054482 |
| protecting peroxidase activity of multilayer enzyme-polyion films using outer catalase layers. | films constructed layer-by-layer on electrodes with architecture {protein/hyaluronic acid (ha)}n containing myoglobin (mb) or horseradish peroxidase (hrp) were protected against protein damage by h2o2 by using outer catalase layers. peroxidase activity for substrate oxidation requires activation by h2o2, but {protein/ha}n films without outer catalase layers are damaged slowly and irreversibly by h2o2. the rate and extent of damage were decreased dramatically by adding outer catalase layers to de ... | 2007 | 18052272 |
| redox state of dipyridamole is a critical determinant for its beneficial antioxidant and antiinflammatory effects. | dipyridamole, a well-known inhibitor of cgmp-dependent phosphodiesterase and the adenosine transporter, reportedly possesses antioxidant properties and attenuates reactive oxygen species (ros) formation in platelet and endothelial cells. the relevance of the redox status of this compound or the mechanism for its redox-dependent effects is unknown. oxidation of dipyridamole by horseradish peroxidase and hydrogen peroxide diminished its fluorescence and attenuated dipyridamole-mediated dpph and fe ... | 2007 | 18049314 |
| evaluation of enzymatic activity on nanoscale polystyrene-block-polymethylmethacrylate diblock copolymer domains. | understanding structural and functional changes of polymeric surface-bound proteins is extremely important as polymers play an increasingly significant role as arrays and substrates in proteomics applications. we carried out, for the first time, quantitative activity measurements of horseradish peroxidase (hrp) enzymes immobilized selectively on the polystyrene domains of microphase-separated polystyrene-block-polymethylmethacrylate ultrathin films. the specific enzymatic activity of hrp adsorbe ... | 2007 | 18044871 |
| spectroscopic studies of interactions involving horseradish peroxidase and tb3+. | the spectroscopic properties of interactions involving horseradish peroxidase (hrp) and tb3+ in the simulated physiological solution was investigated with some electrochemical and spectroscopic methods, such as cyclic voltammetry (cv), circular dichroism (cd), x-ray photoelectron spectroscopy (xps) and synchronous fluorescence (sf). it was found that tb3+ can coordinate with oxygen atoms in carbonyl groups in the peptide chain of hrp, form the complex of tb3+ and hrp (tb-hrp), and then lead to t ... | 2008 | 18024195 |
| evaluation of enzymatic cell treatments for application of card-fish to methanogens. | several enzymatic permeabilization protocols (utilizing lysozyme, proteinase k, achromopeptidase, or recombinant pseudomurein endopeptidase [peiw]) were evaluated for application of in situ hybridization with horseradish peroxidase-labeled oligonucleotide probes and catalyzed reporter deposition (card-fish) to methanogens. in this study, twelve methanogens were selected that have typical cell surface structures: pseudomurein, surface layer, methanochondroitin and sheath. among the treatments tes ... | 2008 | 18022717 |
| dibenzothiophene oxidation by horseradish peroxidase in organic media: effect of the dbt:h2o2 molar ratio and h2o2 addition mode. | its is well known that in the biodesulfurization (bds) process the low water solubility of sulfur compounds hinders its transference from the oil phase to the cells being the rate-limiting step in the metabolism of dibenzothiophenes (dbt). thus sulfur compounds derivatives with high water solubility could be more easily transported increasing the bds efficiency. the present work performed a stepwise evaluation of the enzymatic oxidation of dbt by horseradish peroxidase (hrp). reactions were carr ... | 2008 | 18022671 |
| a comparison of catalytic site intermediates of cytochrome c oxidase and peroxidases. | compounds i and ii of peroxidases such as horseradish peroxidase and cytochrome c peroxidase are relatively well understood catalytic intermediates in terms of their structures and redox states of iron, heme, and associated radical species. the intermediates involved in the oxygen reduction chemistry of the cytochrome c oxidase superfamily are more complicated because of the need for four reducing equivalents and because of the linkage of the oxygen chemistry with vectorial proton translocations ... | 2007 | 18021063 |
| polymer semiconductors as a biosensing platform: peroxidase activity of enzyme bound to organic semiconducting films. | organic polymer semiconductors have unique electronic properties which make them attractive for use in microelectronic and optoelectronic devices fabricated using inexpensive manufacturing processes. in addition, novel chemical and biological sensors have been proposed which make use of the photophysical and electrical properties of conjugated polymer semiconducting films. the work described herein illustrates one such biosensing application by demonstrating successful immobilization of horserad ... | 2007 | 18001900 |