Publications

a separation-free amperometric immunosensor for vitellogenin based on screen-printed carbon arrays modified with a conductive polymer.	a disposable amperometric immunosensor was studied for the rapid detection of carp (carassius auratus) vitellogenin (vtg). the sensor was fabricated based on screen-printed carbon arrays (spcas) containing eight carbon working and an integrated carbon counter electrodes. to construct the sensor, a conducting polymer (poly-terthiophene carboxylic acid) was electropolymerized on the surface of working electrodes and the polymer-coated spcas was characterized by sem. horseradish peroxidase (hrp) an ...	2005	15681194
formation of a misfolded conformation during refolding of hrpa1 in the presence of calcium.	horseradish peroxidase a1 can refold to a native-like structure without binding calcium, originating a ca2+-depleted native state as previously demonstrated. thermal unfolding studies of horseradish peroxidase anionic 1 (hrpa1) have shown that calcium ions present during refolding lead to the appearance of a misfolded conformational state, which cannot incorporate the heme group. this calcium-induced conformational state, ica2+, is less stable than the native state and has distinct secondary and ...	2005	15680244
protein glycosylation analyzed by normal-phase nano-liquid chromatography--mass spectrometry of glycopeptides.	a new method for the mass spectrometric characterization of site-specific protein glycosylation is presented. glycoprotein samples were subjected to unspecific proteolysis by pronase, resulting in glycopeptides with peptide moieties of mostly two to eight amino acids. resulting (glyco-)peptide samples were resolved by nanoscale normal-phase liquid chromatography (lc)-online mass spectrometry (ms). retention depended on the size of the glycan chain and allowed the separation of identical peptide ...	2005	15679358
application of molecular absorption properties of horseradish peroxidase for self-indicating enzymatic interactions and analytical methods.	in this paper an in depth study is presented of the use of the horseradish peroxidase (hrp) enzyme as a self-indicating biorecognition reagent in uv-vis molecular absorption spectrometry. the hrp/h2o2 reaction mechanism in the absence of an external substrate has been clarified, and the interaction between hrp and glucose oxidase (gox) has been studied. it has been demonstrated that gox can act as a substrate of hrp; in both cases the kinetic constants have been obtained and mathematical models ...	2005	15656642
complexes of horseradish peroxidase with formate, acetate, and carbon monoxide.	carbon monoxide, formate, and acetate interact with horseradish peroxidase (hrp) by binding to subsites within the active site. these ligands also bind to catalases, but their interactions are different in the two types of enzymes. formate (notionally the "hydrated" form of carbon monoxide) is oxidized to carbon dioxide by compound i in catalase, while no such reaction is reported to occur in hrp, and the co complex of ferrocatalase can only be obtained indirectly. here we describe high-resoluti ...	2005	15641789
crystal structures of oxidized and reduced stellacyanin from horseradish roots.	umecyanin (umc) is a type 1 copper-containing protein which originates from horseradish roots and belongs to the stellacyanin subclass of the phytocyanins, a ubiquitous family of plant cupredoxins. the crystal structures of cu(ii) and cu(i) umc have been determined at 1.9 and 1.8 a, respectively. the protein has an overall fold similar to those of other phytocyanins. at the active site the cupric ion is coordinated by the n(delta1) atoms of his44 and his90, the s(gamma) of cys85, and the o(epsil ...	2005	15631465
simultaneous in situ detection of rna, dna, and protein using tyramide-coupled immunofluorescence.	the use of tyramide-coupled immunofluorescence at the single cell level provides expedient, clean, and sensitive signals for detection of dna, rna, or proteins. the principle is based on the ability of horseradish peroxidase (hrp) to cleave tyramides into a free radical species with a very short diffusion radius. the free radicals are then covalently bound to electron-rich moieties such as tyrosine in proteins proximal to the targets. here we present protocols for tyramide fluorescent in situ hy ...	2005	15507711
oxidation of milled wood lignin with laccase, tyrosinase and horseradish peroxidase.	in this paper the oxidation of milled wood lignin (mwl), catalysed by three enzymes, i.e. laccase, tyrosinase and horseradish peroxidase (hrp) was studied. the oxidation was followed by measuring the consumption of o(2) during laccase and tyrosinase treatment and of h(2)o(2) during hrp treatment. both laccase and hrp were found to oxidise lignin effectively, whereas the effect of tyrosinase was negligible. the changes in mwl molecular-weight distributions caused in the reactions were analysed by ...	2005	15602685
conjugation of antibodies to horseradish peroxidase.	horseradish peroxidase is coupled to igg antibody in a two-step procedure. in the first step monosaccharide residues in the enzyme are oxidized with periodate to produce aldehyde groups. then, in the second step, the aldehyde groups are allowed to react with amino groups in the igg antibody. the schiff bases formed are reduced and the conjugate is purified by gel filtration.	2005	15596892
reagentless electrochemical biosensor based on the multi-wall carbon nanotubes and nanogold particles composite film.	a novel method was used to prepare the nano-composite by assembling nanogold (ng) particles on the multiwall carbon nanotubes (mwnts) surface. the nano-composite could be immobilized on a glassy carbon (gc) electrode to get a novel modified electrode. the electrode can easily immobilize the horseradish peroxidase (hrp) molecules to construct a reagentless biosensor. the ng particles in the composite film have a good biological compatibility. and due to the existence of quinone groups on the mwnt ...	2005	15574389
investigating the cause of the alkaline transition of phytocyanins.	the phytocyanins are a family of plant cupredoxins that have been subdivided into the stellacyanins, plantacyanins, and uclacyanins. all of these proteins possess the typical type 1 his(2)cys equatorial ligand set at their mononuclear copper sites, but the stellacyanins have an axial gln ligand in place of the weakly coordinated met of the plantacyanins, uclacyanins, and most other cupredoxins. the stellacyanins exhibit altered visible, epr, and paramagnetic (1)h nmr spectra at elevated ph value ...	2005	15723550
the intrinsic axial ligand effect on propene oxidation by horseradish peroxidase versus cytochrome p450 enzymes.	the axial ligand effect on reactivity of heme enzymes is explored by means of density functional theoretical calculations of the oxidation reactions of propene by a model compound i species of horseradish peroxidase (hrp). the results are assessed vis-a-vis those of cytochrome p450 compound i. it is shown that the two enzymatic species perform c=c epoxidation and c-h hydroxylation in a multistate reactivity scenario with fe(iii) and fe(iv) electromeric situations and two different spin states, d ...	2005	15723206
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
hofmeister effects in biology: effect of choline addition on the salt-induced super activity of horseradish peroxidase and its implication for salt resistance of plants.	the effect of choline addition on the salt-induced super activity of horseradish peroxidase (hrp) is investigated. hrp is presented in the literature as an efficient h(2)o(2) scavenger, and choline is the precursor of glycine betaine, a strong osmoprotectant molecule. both the regulations of h(2)o(2) and of osmoprotectant concentrations are implicated in plants in order to counteract salt-induced cell damage. for the oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium ...	2005	16853099
horseradish peroxidase renaturation is less efficient at lower protein concentrations.	renaturation of horseradish peroxidase from guainidine hydrochloride has been studied. although refolding of the secondary structure was complete, only partial heme incorporation and recovery of enzymatic activity were observed. heme capturing became less efficient at lower peroxidase concentrations: the refolding yield decreased from 60% at 1 microm to 10% at 0.1 microm concentration of the protein. probing with conformation-sensitive antibodies indicated structural differences between peroxida ...	2005	16522186
sequential injection chemiluminescence immunoassay for anionic surfactants using magnetic microbeads immobilized with an antibody.	a rapid and sensitive immunoassay for the determination of linear alkylbenzene sulfonates (las) is described. the method involves a sequential injection analysis (sia) system equipped with a chemiluminescence detector and a neodymium magnet. magnetic beads, to which an anti-las monoclonal antibody was immobilized, were used as a solid support in an immunoassay. the introduction, trapping and release of the magnetic beads in the flow cell were controlled by means of a neodymium magnet and adjusti ...	2005	18970310
quantum dots-based reverse phase protein microarray.	cdse nanocrystals, also called quantum dots (qdots) are a novel class of fluorophores, which have a diameter of a few nanometers and possess high quantum yield, tunable emission wavelength and photostability. they are an attractive alternative to conventional fluorescent dyes. quantum dots can be silanized to be soluble in aqueous solution under biological conditions, and thus be used in bio-detection. in this study, we established a novel qdot-based technology platform that can perform accurate ...	2005	18970191
a peroxidase-tetrathiafulvalene biosensor based on self-assembled monolayer modified au electrodes for the flow-injection determination of hydrogen peroxide.	the construction and performance under flow-injection conditions of an integrated amperometric biosensor for hydrogen peroxide is reported. the design of the bioelectrode is based on a mercaptopropionic acid (mpa) self-assembled monolayer (sam) modified gold disk electrode on which horseradish peroxidase (hrp, 24.3u) was immobilized by cross-linking with glutaraldehyde together with the mediator tetrathiafulvalene (ttf, 1mumol), which was entrapped in the three-dimensional aggregate formed. the ...	2005	18970123
continuous-flow system for horseradish peroxidase enzyme assay comprising a packed-column, an amperometric detector and a rotating bioreactor.	the roles of chemical kinetics and mass transfer in three types of bioreactors (packed-column reactors, rotating disk bioreactors and amperometric detector), used with continuous-flow sample/reagent(s) processing, are discussed in detail. a normalized quantitative comparison between these types of reactors clearly shows that rotating disk reactors afford a significantly more efficient utilization of active sites and permit the effective utilization of very small amounts of biocatalysts. horserad ...	2005	18969967
direct electrochemistry and electrocatalysis of heme-protein based on n,n-dimethylformamide film electrode.	the heme-protein including myoglobin (mb), hemoglobin (hb) and horseradish peroxidase (hrp) were immobilized on normal graphite electrode by using n,n-dimethylformamide (dmf). the proteins undergo direct electron-transfer reactions. the current is linearly dependent on the scan rate, indicating that the direct electrochemistry of heme-protein in that case is a surface-controlled electrode process. the e degrees s are linearly dependent on solution ph (redox-bohr effect), indicating that the elec ...	2006	18970822
photochemical activation of a polycarbonate surface for covalent immobilization of a protein ligand.	polycarbonate-a thermostable polymer is activated by a simple and rapid method using a photolinker, 1-fluoro-2-nitro-4-azidobenzene (fnab) for covalent immobilization of a biomolecule. horseradish peroxidase (hrp) is used as a model enzyme to check the efficacy of the activated surface. hrp is immobilized on the activated polycarbonate surface without addition of any reagent or catalyst and is found to give 2-2.5-fold increase in absorbance with the substrate as compared to the directly adsorbed ...	2006	18970818
gold colloid-bienzyme conjugates for glucose detection utilizing surface-enhanced raman scattering.	it is difficult to detect glucose by surface-enhanced raman spectroscopy (sers) due to the small normal raman cross-section and the weak adsorption of glucose molecules on the surface of noble metal. a simple and fast method is proposed in this paper for the detection of glucose based on sers signal of the enzyme reaction product and the difficulties have been circumvented. gold colloids modified by horseradish peroxidase and glucose oxidase (hrp/god-gold colloids) are added to the mixture of o- ...	2006	18970804
determination of clenbuterol by capillary electrophoresis immunoassay with chemiluminescence detection.	a competitive immunoassay for clenbuterol (clb) based on capillary electrophoresis with chemiluminescence (cl) detection was established. the method was based on the competitive reaction of horseradish peroxidase (hrp)-labeled clb (clb-hrp) and free clb with anti-clb antiserum. the factors affecting the electrophoresis and cl detection were systematically investigated with hrp as a model sample. under the optimal conditions, the tracer clb-hrp and the immunoassay complex were separated, and the ...	2006	18970774
a new kinetic method for quantification phenoxyl free radicals.	in this work, a new kinetic method was proposed for quantification phenoxyl radicals generated in enzyme reaction. instead of direct detecting the spectral signals of phenoxyl radicals, a molecular probe, the reduced form of nicotinamide adenine dinucleotide (nadh), was employed to indicate the formation of phenoxyl free radicals. it was found that the reactions of nadh and phenoxyl radicals are very fast, but can be followed by using stopped-flow fast scanning spectrophotometric technique. the ...	2006	18970770
enzymatic rotating biosensor for ciprofloxacin determination.	the high sensitivity that can be attained using an enzymatic system and mediated by catechol has been verified by on-line interfacing of a rotating biosensor and continuous flow/stopped-flow/continuous-flow processing. horseradish peroxidase, hrp [ec 1.11.1.7], immobilized on a rotating disk, in the presence of hydrogen peroxide, catalyzed the oxidation of catechol, whose back electrochemical reduction was detected on a glassy carbon electrode surface at -200mv. thus, when ciprofloxacin (cf) was ...	2006	18970624
new fluorometric enzyme immunoassay for 17beta-estradiol by homogeneous reaction using biotinylated estradiol.	a new fluorometric enzyme immunoassay for 17beta-estradiol (e2) using biotinylated estradiol (be) as a probe ligand, is described. in this method, e2 is detected indirectly by a solid-phase avidin-biotin binding assay, in which the biotin is immobilized on a microtiter plate (biotin-plate). after the competitive reaction between e2 and be for the anti-e2 antibody in solution, the free e2 and be are separated from the bound forms by means of ultrafiltration. the concentration of be in the solutio ...	2006	18970619
study and application of perturbation of peroxynitrite on peroxidase-oxidase oscillation.	peroxynitrite was one of the important reactive oxygen species (ros) which have been focused for many years. peroxynitrite is an extremely strong and reactive oxidant which can cause many diseases linked to inflammatory processes and autoimmune diabetes, etc. ros can significantly react with peroxidase and nicotinamide adanine dinucleotide (nadh) which is linked to numerous biological processes. nadh, nad and horseradish peroxidase (hrp) were included in peroxidase-oxidase (po) oscillation, diss ...	2006	18970596
enzymatic rotating biosensor for cysteine and glutathione determination in a fia system.	the high sensitivity that can be attained using an enzymatic system and mediated by catechols has been verified by on-line interfacing of a rotating biosensor and continuous flow/stopped-flow/continuous-flow processing. horseradish peroxidase, hrp, [ec 1.11.1.7], immobilized on a rotating disk, in presence of hydrogen peroxide catalyzed the oxidation of catechols, whose back electrochemical reduction was detected on glassy carbon electrode surface at -150mv. thus, when l-cysteine (cys) or glutat ...	2006	18970470
fia-near-infrared spectrofluorimetric trace determination of hydrogen peroxide using tricarchlorobocyanine dye (cy.7.cl) and horseradish peroxidase (hrp).	a new kind of near-infrared fluorescence agent, tricarbochlorocyanine dye (cy.7.cl), had been synthesized in house and used for near-infrared spectrofluorimetric determination of hydrogen peroxide (h(2)o(2)) by flow injection analysis (fia) for the first time. the oxidation reaction of cy.7.cl with h(2)o(2) occurred under the catalysis of horseradish peroxidase (hrp) and it was studied in detail. the possible reaction mechanism was discussed. under optimal experimental conditions, fluorescence f ...	2006	18970404
composite film of carbon nanotubes and chitosan for preparation of amperometric hydrogen peroxide biosensor.	a new amperometric biosensor for hydrogen peroxide was developed based on cross-linking horseradish peroxidase (hrp) by glutaraldehyde with multiwall carbon nanotubes/chitosan (mwnts/chitosan) composite film coated on a glassy carbon electrode. mwnts were firstly dissolved in a chitosan solution. then the morphology of mwnts/chitosan composite film was characterized by field-emission scanning electron microscopy. the results showed that mwnts were well soluble in chitosan and robust films could ...	2006	18970381
cytochrome p450-catalyzed oxidation of n-benzyl-n-cyclopropylamine generates both cyclopropanone hydrate and 3-hydroxypropionaldehyde via hydrogen abstraction, not single electron transfer.	the suicide substrate activity of n-benzyl-n-cyclopropylamine (1) and n-benzyl-n-(1'-methylcyclopropyl)amine (2) toward cytochrome p450 and other enzymes has been explained by a mechanism involving single electron transfer (set) oxidation, followed by ring-opening of the aminium radical cation (protonated aminyl radical) and reaction with the p450 active site. although the set oxidation of n-cyclopropyl-n-methylaniline (3) by horseradish peroxidase leads exclusively to ring-opened (non-cycloprop ...	2006	16522116
amperometric choline biosensor fabricated through electrostatic assembly of bienzyme/polyelectrolyte hybrid layers on carbon nanotubes.	we report a flow injection amperometric choline biosensor based on the electrostatic assembly of the choline oxidase (cho) enzyme and a bienzyme of cho and horseradish peroxidase (hrp) onto multi-wall carbon nanotubes (mwcnt) modified glassy carbon (gc) electrodes. these choline biosensors were fabricated by immobilization of enzymes on the negatively charged mwcnt surface through alternately assembling a cationic poly(diallydimethylammonium chloride) (pdda) layer and an enzyme layer. using this ...	2006	16568162
are the biological properties of kaempferol determined by its oxidation products?	although flavonoid molecules have attracted considerable interest in recent years because of their antioxidant effect, there are considerable differences in their chemical properties. electron paramagnetic resonance (epr) spectroscopy was used to compare the oxidative free radical chemistry of two such molecules, kaempferol and luteolin, which have the same empirical formula but differ in the position of one oh group. whereas the basic flavonoid structure remains intact in luteolin, structural c ...	2006	16551578
quantitative structure-activity relationship based quantification of the impacts of enzyme-substrate binding on rates of peroxidase-mediated reactions of estrogenic phenolic chemicals.	the initial rates of horseradish peroxidase (hrp)-mediated enzymatic reactions of 15 assorted aqueous phase phenolic chemicals were studied. the associated reaction rate constants were found to correlate quantitatively with two independent variables: the highest-occupied molecular orbital energy (e(homo)) defining the intrinsic redox reactivities of the phenolic substrates and the distance between a substrate and the deltan of his42's imidazole ring in an hrp/substrate binding complex, obtained ...	2006	16551113
microcantilevers modified by horseradish peroxidase intercalated nano-assembly for hydrogen peroxide detection.	detection of hydrogen peroxide is of industry interest and of biological importance. here we report a new approach to hydrogen peroxide measurement using multilayer modified microcantilevers. through a layer-by-layer nanoassembly technique, horseradish peroxidase was intercalated into a nanoscale multilayer assembly on one surface of microcantilevers. these enzyme-functionalized microcantilevers deflected in response to hydrogen peroxide concentrations in the nanomolar level. the magnitudes of b ...	2006	16512409
structures of the high-valent metal-ion haem-oxygen intermediates in peroxidases, oxygenases and catalases.	peroxidases, oxygenases and catalases have similar high-valent metal-ion intermediates in their respective reaction cycles. in this review, haem-based examples will be discussed. the intermediates of the haem-containing enzymes have been extensively studied for many years by different spectroscopic methods like uv-vis, epr (electron paramagnetic resonance), resonance raman, mössbauer and mcd (magnetic circular dichroism). the first crystal structure of one of these high-valent intermediates was ...	2006	16510192
two-state reactivity, electromerism, tautomerism, and "surprise" isomers in the formation of compound ii of the enzyme horseradish peroxidase from the principal species, compound i.	qm and qm/mm calculations on compound ii, the enigmatic species in the catalytic cycle of the horseradish peroxidase enzyme, reveal six low-lying isomers. the principal isomer is the triplet oxo-ferryl form (porfe(iv)=o) that yields the hydroxo-ferryl isomer (porfe(iv)-oh+). these are the only forms observed in experimental studies. theory shows, however, that these are the least stable isomers of compound ii. the two most stable forms are the singlet and triplet states of the por+*fe(iii)-oh el ...	2006	16787083
synthetic nanocrystalline diamond as a third-generation biosensor support.	horseradish peroxidase (hrp) has been immobilized on the surface of functionalized nanocrystalline diamond (ncd) thin films. the structure of the modified ncd surface as well as the electrochemical behavior of the whole system was characterized by impedance spectroscopy and cyclic voltammetry. the proximity of hrp heme groups to the ncd surface allowed direct electron transfer between them, resulting in two separated one-electron-transfer peaks at 0.05 v and 0.29 v vs ag/agcl, corresponding to t ...	2006	16768516
enzymatic polymerization of coniferyl alcohol in the presence of cyclodextrins.	the dehydrogenative polymerization of coniferyl alcohol by horseradish peroxidase was performed in 0.10 m phosphate buffer at 27 degrees c. dehydrogenative polymer (dhp) from coniferyl alcohol was characterized by size exclusion chromatography (sec) and nuclear magnetic resonance (nmr) spectroscopy. the ratio of 8-o-4':8-5':8-8' linkages was determined by the 1h nmr spectrum of dhp acetate which had good solubility. in "end-wise like" polymerization (the slow addition of hydrogen peroxide), addi ...	2006	16768416
new approach for the detection of peptide- and protein-based radicals using a pre-fluorescent probe.	a novel application for pre-fluorescent probes in the detection of peptide- and protein-based radicals is proposed. pre-fluorescent probes combine a fluorescent moiety labeled with a paramagnetic nitroxide that acts as a fluorescence quencher. trapping of a radical by the nitroxide group restores the fluorescence properties. the increase in fluorescence intensity with time reflects the formation and quenching of free radicals and can be employed for the quantitative evaluation of yields and kine ...	2006	16542572
two coupled enzymes perform in parallel the 'and' and 'inhiband' logic gate operations.	the coupled activation of two enzymes: glucose dehydrogenase (gdh) and horseradish peroxidase (hrp), is used to construct the parallel-operating and and inhiband logic gates. the added substrates for the respective enzymes, glucose and h(2)o(2), act as the gate inputs, while the biocatalytically generated nadh and gluconic acid provide the output signals that follow the operations of the gates. the two gates are generated in the same vial, thus allowing the logic operations to take place in para ...	2006	16525539
metabolic biotinylation of cell surface receptors for in vivo imaging.	we have developed a versatile, potent technique for imaging cells in culture and in vivo by expressing a metabolically biotinylated cell-surface receptor and visualizing it with labeled streptavidin moieties. the recombinant reporter protein, which incorporates a biotin acceptor peptide (bap) between an n-terminal signal sequence and a transmembrane domain, (bap-tm) was efficiently biotinylated by endogenous biotin ligase in mammalian cells with the biotin displayed on the cell surface. tumors e ...	2006	16628210
[efficacy and safety profile of a herbal drug containing nasturtium herb and horseradish root in acute sinusitis, acute bronchitis and acute urinary tract infection in comparison with other treatments in the daily practice/results of a prospective cohort study].	in a prospective cohort study from 251 centers in germany patients with age of 4 years or above who were treated due to acute sinusitis, bronchitis or urinary tract infections (uti) in the period from 1st march 2004 - 30th july 2005, were elected. they were included in the study analysis, if they had no exclusion criteria (severe diseases, need for antibiotic therapy, participation in another trial) and came to the final investigation. the patients were treated either with the nasturtium herb an ...	2006	16618018
co-lyophilization with d-proline greatly enhances peroxidase's stereoselectivity in a non-aqueous medium.	the impact of co-lyophilizing horseradish peroxidase (hrp) with numerous amino acids and other chiral excipients on the enzyme's subsequent stereoselectivity [e(s/r)] in the sulfoxidation of thioanisole in 2-propanol was systematically investigated. while many improved the stereoselectivity of (and significantly activated) hrp, the greatest effect was observed with d-proline which enhanced the e(s/r) value by over an order of magnitude from synthetically meaningless to useful.	2006	16614892
classification of chemical and biological warfare agent simulants by surface-enhanced raman spectroscopy and multivariate statistical techniques.	initial results demonstrating the ability to classify surface-enhanced raman (sers) spectra of chemical and biological warfare agent simulants are presented. the spectra of two endospores (b. subtilis and b. atrophaeus), two chemical agent simulants (dimethyl methylphosphonate (dmmp) and diethyl methylphosphonate (demp)), and two toxin simulants (ovalbumin and horseradish peroxidase) were studied on multiple substrates fabricated from colloidal gold adsorbed onto a silanized quartz surface. the ...	2006	16613630
kinetic modelling of phenol co-oxidation using horseradish peroxidase.	phenol is an industrial pollutant and its removal from industrial wastewaters is of great importance. in order to design optimised phenol removal procedures by using horseradish peroxidase-based systems, there are some points that have to be dealt with. one of the most important issues is the need for reliable kinetics as this is one of the difficulties found during process scale-up. although simplified kinetics can be used for limited ranges of operating conditions, they are not usually reliabl ...	2006	16612606
building three-dimensional nanostructures with active enzymes by surface templated layer-by-layer assembly.	we show that well-defined three-dimensional nanostructures of functional enzymes can be controllably fabricated by layer-by-layer assembly of avidin and biotinylated horseradish peroxidase on micro-contact printing patterned surface templates.	2006	16609783
modeling suberization with peroxidase-catalyzed polymerization of hydroxycinnamic acids: cross-coupling and dimerization reactions.	an anionic potato peroxidase (ec 1.11.1.7, app) thought to be involved in suberization after wounding was isolated from slices of solanum tuberosum in order to elucidate the first steps of dehydrogenative polymerization between pairs of different hydroxycinnamic acids (fa, cafa, ca and sa) present in wound-healing plant tissues. use of a commercial horseradish peroxidase (hrp)-h2o2 catalytic system gave the identical major products in these coupling reactions, providing sufficient quantities for ...	2006	16524605
quenchers induce wavelength dependence on protein fluorescence lifetimes.	we have analysed the picosecond resolved fluorescence emission decay of horseradish peroxidase a2 and of hew lysozyme acquired with a streak camera. analyses of the fluorescence decay data of both proteins revealed that the dynamics of the decay is dependent on the emission wavelength. our data strongly indicates that resonance energy transfer occurring between aromatic residues and different protein fluorescence quencher groups, and the nature of the quencher groups, are the causes of the obser ...	2006	16794870
redox properties of the fe3+/fe2+ couple in arthromyces ramosus class ii peroxidase and its cyanide adduct.	the thermodynamics of the one-electron reduction of the ferric heme in free and cyanide-bound arthromyces ramosus peroxidase (arp), a class ii plant peroxidase, were determined through spectro-electrochemical experiments. the data were compared with those for class iii horseradish peroxidase c (hrp) and its cyanide adduct, and were interpreted in terms of ligand binding features, electrostatic effects and solvent accessible surface area of the heme group and of catalytically relevant residues in ...	2006	16791642
aggregation behavior of giant amphiphiles prepared by cofactor reconstitution.	we report on biohybrid surfactants, termed "giant amphiphiles", in which a protein or an enzyme acts as the polar head group and a synthetic polymer as the apolar tail. it is demonstrated that the modification of horseradish peroxidase (hrp) and myoglobin (mb) with an apolar polymer chain through the cofactor reconstitution method yields giant amphiphiles that form spherical aggregates (vesicles) in aqueous solution. both hrp and mb retain their original functionality when modified with a single ...	2006	16688714
in situ encapsulation of horseradish peroxidase in electrospun porous silica fibers for potential biosensor applications.	nanoporous silica nanofibers have been employed as a matrix to encapsulate horseradish peroxide enzymes via a simple electrospinning method. a viscous solution of prehydrolyzed tetramethyl orthosilicate, beta-d-glucose, poly(vinyl alcohol), and enzymes were employed as spinning solution to generate porous fibers in the form of nonwoven mats. the silica fiber mats thus produced have a high surface area because of the small diameter (100 to 200 nm) of the fibers as well as the extreme porosity (2 ...	2006	16683848
bienzyme sensors based on novel polymethylferrocenyl dendrimers.	amperometric bienzyme electrodes with horseradish peroxidase (hrp) and glucose oxidase (gox) co-immobilized on polymethylferrocenyl dendrimers deposited onto platinum electrodes have been used for determination of the hydrogen peroxide produced by the oxidase during the enzymatic reaction. the redox dendrimers consist of flexible poly(propylenimine) dendrimer cores functionalised with octamethylferrocenyl units. the effects of dendrimer generation, the thickness of the dendrimer layer, substrate ...	2006	16673089
role of heme-protein covalent bonds in mammalian peroxidases. protection of the heme by a single engineered heme-protein link in horseradish peroxidase.	oxidation of scn-, br-, and cl- (x-) by horseradish peroxidase (hrp) and other plant and fungal peroxidases results in the addition of hox to the heme vinyl group. this reaction is not observed with lactoperoxidase (lpo), in which the heme is covalently bound to the protein via two ester bonds between carboxylic side chains and heme methyl groups. to test the hypothesis that the heme of lpo and other mammalian peroxidases is protected from vinyl group modification by the hemeprotein covalent bon ...	2006	16651262
ph-dependent regulation of myeloperoxidase activity.	the balance between peroxidase and chlorinating activities of myeloperoxidase (mpo) is very important for the enhancement of antimicrobial action and prevention of damage caused by hypochlorite. in the present paper, the peroxidase and chlorinating activities have been studied at various ph values. the possibility of using neutrophil protein solution for the evaluation of mpo activity has been demonstrated. it is shown that at neutral ph mpo had higher affinity to peroxidase substrate guaiacol: ...	2006	16827659
horseradish and soybean peroxidases: comparable tools for alternative niches?	horseradish and soybean peroxidases (hrp and sbp, respectively) are useful biotechnological tools. hrp is often termed the classical plant heme peroxidase and although it has been studied for decades, our understanding has deepened since its cloning and subsequent expression, enabling numerous mutational and protein engineering studies. sbp, however, has been neglected until recently, despite offering a real alternative to hrp: sbp actually outperforms hrp in terms of stability and is now used i ...	2006	16815578
magnetic spin effects in enzymatic reactions: radical oxidation of nadh by horseradish peroxidase.	a description of the elementary steps of the horseradish peroxidase (hrp)-catalyzed oxidation of nadh is presented, along with a quantitative analysis of the magnetic-field dependence of the enzymatic reaction. in the absence of h(2)o(2), the catalytic cycle begins with single-electron transfer from nadh to native hrp to form the nadh(.+) radical cation and the ferroperoxidase intermediate (per(2+)). the theoretical framework for the magnetic-field dependent recombination of radical pairs has be ...	2006	16802831
tailoring of horseradish peroxidase activity in cationic water-in-oil microemulsions.	horseradish peroxidase (hrp) in cationic water-in-oil (w/o) microemulsions has always been ignored in reverse micellar enzymology, mainly because cationic surfactants are inhibitors of enzyme peroxidase. in the present study, for the first time, we have successfully introduced the cationic w/o microemulsion as an attractive host for efficient hrp activity. to this notion, much improved activity of hrp was observed in the w/o microemulsion of cetyltrimethylammonium bromide (ctab) with an increase ...	2006	16649765
a new, sensitive method for enzyme kinetic studies of scarce glucosides.	the maize beta-glucosidase zm-p60.1 is important for the regulation of plant development through its role in the targeted release of free cytokinins from cytokinin-o-glucosides, their inactive storage forms. enzyme kinetics studies using these scarce substrates close to physiological concentrations are difficult due to two reasons: (a) available methods are mainly suited for end-point kinetics. (b) these methods are not sufficiently sensitive when using scarce glucoside substrates. we developed ...	2006	16730803
the poulos-kraut mechanism of compound i formation in horseradish peroxidase: a qm/mm study.	qm/mm calculations are used to elucidate the poulos-kraut (poulos, t. l.; kraut, j. j. biol. chem. 1980, 255, 8199-8205) mechanism of o-o bond activation and compound i (cpd i) formation in hrp, in conditions corresponding to neutral to basic ph. attempts to generate compound i directly from the fe(h2o2) complex by migrating the proton from the proximal oxygen to the distal one (1,2- proton shift) result in high barriers. the lowest energy mechanism was found to involve initial deprotonation of ...	2006	16722763
molecular recognition of mono- and disaccharides through interaction with p-iodophenylboronic acid in capillary electrophoresis with a chemiluminescence detection system.	molecular recognition of mono- and disaccharides was performed making use of the interaction between their diol groups and p-iodophenylboronic acid in capillary electrophoresis (ce) with a chemiluminescence (cl) detection system. p-iodophenylboronic acid acted as an enhancer for luminol-horseradish peroxidase-hydrogen peroxide cl reaction. p-iodophenylboronic acid was injected as a sample into the present system to give a cl peak on the electropherogram. the cl intensities were examined using ru ...	2006	16716339
chemiluminescent-based method for heme determination by reconstitution with horseradish peroxidase apo-enzyme.		2006	16701068
the role of stigma peroxidases in flowering plants: insights from further characterization of a stigma-specific peroxidase (ssp) from senecio squalidus (asteraceae).	angiosperm stigmas have long been known to exhibit high levels of peroxidase activity when they are mature and most receptive to pollen but the biological function of stigma peroxidases is not known. a novel stigma-specific class iii peroxidase gene, ssp (stigma-specific peroxidase) expressed exclusively in the stigmas of senecio squalidus l. (asteraceae) has recently been identified. expression of ssp is confined to the specialized secretory cells (papillae) that compose the stigma epidermis. t ...	2006	16698818
conformational changes and activity alterations induced by nickel ion in horseradish peroxidase.	conformational changes induced by the binding of nickel to horseradish peroxidase c (hrpc) were studied by electronic absorption spectroscopy, fluorescence spectroscopy and circular dichroism spectroscopy. incubation of hrpc with various concentrations of ni(2+) for 5 minutes resulted in changes in the enzyme absorption spectrum, including variations in the intensities of the soret, beta and charge transfer (ct1) bands absorption, shift in the soret, beta and ct1 bands maxima and absorption incr ...	2006	16697100
flow-injection chemiluminescent immunoassay for alpha-fetoprotein based on epoxysilane modified glass microbeads.	a flow-injection chemiluminescent immunoassay system based on a novel transparent immunoaffinity reactor is proposed for the quantitation of alpha-fetoprotein. the reactor prepared with alpha-fetoprotein immobilized epoxysilane modified glass microbeads was used as an immunosensor for chemiluminescent detection. with a non-competitive immunoassay format, the proposed immunosensor system is a low cost, flexible and rapid assay for alpha-fetoprotein. after an off-line incubation of the analyte alp ...	2006	16647079
a new terbium(iii) chelate as an efficient singlet oxygen fluorescence probe.	a terbium(iii) chelate fluorescence probe for detection of singlet oxygen (1o2) in aqueous media, n,n,n1,n1-[2,6-bis(3'-aminomethyl-1'-pyrazolyl)-4-(9''-anthryl)pyridine] tetrakis (acetate)-tb3+ (pata-tb3+), was designed and synthesized. the new chelate is highly water soluble, is almost nonfluorescent, and can specifically react with 1o2 to yield a strongly fluorescent chelate, the endoperoxide of pata-tb3+, accompanied by a remarkable increase in the fluorescence quantum yield from 0.46 to 10. ...	2006	16632124
galactose oxidase action on galactose containing glycolipids--a fluorescence method.	features that alter the glycolipid sugar headgroup accessibility at the membrane interface have been studied in bilayer lipid model vesicles using a fluorescence technique with the enzyme galactose oxidase. the effects on oxidation caused by variation in the hydrophobic moiety of galactosylceramide or the membrane environment for galactosylceramide, monogalactosyldiacylglycerol and digalactosyldiacylglycerol were studied. for this study we combined the galactose oxidase method for determining th ...	2006	16647698
impact of aging on the formation of bound residues after peroxidase-mediated treatment of 2,4-dcp contaminated soils.	this study evaluated the impact of solute-soil contact time on the formation of "bound" residue in two surface soils exposed to solutions containing 2,4-dichlorophenol (dcp) or dcp polymerization products (dpp). dpp was generated by horseradish peroxidase (hrp) mediated oxidative polymerization of 14c-labeled dcp in the soil slurry. soils were preloaded with dcp or dpp for durations ranging from 2 h to 84 days. bound residue was described as solute that was resistant to methanol extraction. alka ...	2006	16749713
delivery of nanogram payloads using magnetic porous silicon microcarriers.	a transport and delivery system for nanogram quantities of molecular species that does not use microfluidic channels, pumps, or valves is described. microparticles consisting of magnetic porous silicon are prepared, and loading and delivery of an enzymatic payload are demonstrated. the high porosity (60%) porous si host particles are made magnetic by infusion of superparamagnetic iron oxide nanoparticles (30 nm-diameter magnetite, fe(3)o(4)) under oxidative conditions. after magnetite incorporat ...	2006	16738731
isolation and characterization of the first putative peroxidase gene from oilseed rape (brassica napus) which is highly homologous to hrpc.	a new gene, designated as bnprx (genbank accession no. dq078754), was isolated from oilseed rape (brassica napus) by smart rapid amplification of cdna ends (race). the full-length cdna is 1307 bp long and contains a 1062 bp open reading frame (orf), which encodes a 354 amino acid peroxidase precursor, with a 31 aa n-terminal signal peptide and a 15 aa c-terminal propeptide. the putative protein has a molecular weight of 38.86 kda and a calculated pi of 5.85. bnprx shares high identity with hrpc ...	2006	16855866
multiplexed analyte and oligonucleotide detection on microarrays using several redox enzymes in conjunction with electrochemical detection.	we show that multiple enzyme tags may be used in an immunoassay format or for the detection of sequence-specific dna on microarrays. the assays may be multiplexed and monitored under separate solution and voltage differences. thus, the detection method relies on an electrochemical detection format, whereby multiple enzymes can be sensed. in our case we utilize horseradish peroxidase, laccase, and glucose dehydrogenase as enzymes attached to specific antibodies or to streptavidin.	2006	16874377
infrared absorption study of the heme pocket dynamics of carbonmonoxyheme proteins.	the temperature dependencies of the infrared absorption co bands of carboxy complexes of horseradish peroxidase (hrp(co)) in glycerol/water mixture at ph 6.0 and 9.3 are interpreted using the theory of optical absorption bandshape. the bands' anharmonic behavior is explained assuming that there is a higher-energy set of conformational substates (css(h)), which are populated upon heating and correspond to the protein substates with disordered water molecules in the heme pocket. analysis of the se ...	2006	16980362
nanophase-separated amphiphilic conetworks as versatile matrixes for optical chemical and biochemical sensors.	as a novel class of sensor matrixes, nanophase-separated amphiphilic polymeric conetworks (apcns) open a new dimension for optical chemical and biochemical sensing. these conetworks consist of a hydrophilic phase-we used poly(2-hydroxyethyl acrylate), poly(2-(dimethylamino)ethyl acrylate), or polycationic poly(2-(trimethylammonium)ethyl acrylate)-and of a hydrophobic phase-poly(dimethylsiloxane). sensors can be prepared by simple impregnation of the matrix. due to nanophase separation, there is ...	2006	16970311
dna-directed assembly of polyanilines: modified cytosine nucleotides transfer sequence programmability to a conjoined polymer.	a series of polyaniline (pani) oligomers was constructed from monomer units covalently linked to duplex dna through n-(2-aminoethyl) groups bonded through cytosines. dna oligomers containing the aniline monomers were treated with horseradish peroxidase (hrp) and h2o2 under conditions known to cause polymerization of aniline. no change in the absorption spectrum of the dna was observed for samples containing fewer than four contiguous aniline groups. however, for oligomers containing four, five, ...	2006	17090004
an efficient proton-coupled electron-transfer process during oxidation of ferulic acid by horseradish peroxidase: coming full cycle.	quantum mechanics/molecular mechanics calculations were utilized to study the process of oxidation of a native substrate (ferulic acid) by the active species of horseradish peroxidase (dunford, h. b. heme peroxidases; wiley-vch: new york, 1999), compound i and compound ii, and the manner by which the enzyme returns to its resting state. the results match experimental findings and reveal additional novel features. the calculations demonstrate that both oxidation processes are initiated by a proto ...	2006	17044722
receptive field structure-function correlates in developing turtle retinal ganglion cells.	mature retinal ganglion cells (rgcs) have distinct morphologies that often reflect specialized functional properties such as on and off responses. but the structural correlates of many complex receptive field (rf) properties (e.g. responses to motion) remain to be deciphered. in this study, we have investigated whether motion anisotropies (non-homogeneities) characteristic of embryonic turtle rgcs arise from immature dendritic arborization in these cells. to test this hypothesis, we have looked ...	2006	16930408
stacked films immobilization of mbth in nafion/sol-gel silicate and horseradish peroxidase in chitosan for the determination of phenolic compounds.	the stacked-film immobilization of 3-methyl-2-benzothiazolinone hydrazone (mbth) in hybrid nafion/sol-gel silicate film and horseradish peroxidase (hrp) in chitosan, performed in order to allow the determination of phenolic compounds, was investigated via an optical method. the stacked films were deposited onto a microscope glass slide by a spin-coating technique. the quinone or free radical product formed by the enzymatic reactions of phenolic compounds interacts with mbth to form azo-dye produ ...	2006	17031625
early neural activity and dendritic growth in turtle retinal ganglion cells.	early neural activity, both prenatal spontaneous bursts and early visual experience, is believed to be important for dendritic proliferation and for the maturation of neural circuitry in the developing retina. in this study, we have investigated the possible role of early neural activity in shaping developing turtle retinal ganglion cell (rgc) dendritic arbors. rgcs were back-labelled from the optic nerve with horseradish peroxidase (hrp). changes in dendritic growth patterns were examined acros ...	2006	16930407
inactivation of alpha1-antiproteinase induced by phenylbutazone: participation of peroxyl radicals and hydroperoxide.	to clarify the action of a side-effect of phenylbutazone, we investigated the inactivation of alpha(1)-antiproteinase induced by phenylbutazone in the presence of horseradish peroxidase (hrp) and h(2)o(2) (hrp-h(2)o(2)). the activity of alpha(1)-antiproteinase was rapidly lost during the interaction of phenylbutazone with hrp-h(2)o(2) under aerobic conditions. phenylbutazone showed a marked spectral change under aerobic conditions but not under anaerobic conditions. spin trap agents were very ef ...	2006	16930300
ultrafast pump-probe study of excited-state charge-transfer dynamics in umecyanin from horseradish root.	we have applied femtosecond pump-probe spectroscopy to investigate the excited-state dynamics of umecyanin from horseradish roots, by exciting its 600-nm ligand-to-metal charge-transfer band with a 15-fs pulse and probing over a broad range in the visible region. the decay of the pump-induced ground-state bleaching is modulated by clearly visible oscillations and occurs exponentially with a time constant depending on the observed spectral component of the transmission difference signal, ranging ...	2006	16928024
lateral spread of an amplification signal using an enzymatic system on a conductive surface.	in this letter, we report a novel signal amplification phenomenon that rapidly and dramatically increases both the magnitude and the lateral extent of the original signal. this phenomenon utilizes an enzyme immobilized on a conductive surface to generate amplified signals at locations remote from the original site of enzyme activity. the result is demonstrated on a microfluidic platform using the established precipitating enzyme-substrate system of horseradish peroxidase (hrp) and 3,3',5,5'-tetr ...	2006	16922518
horseradish peroxidase inhibition and antioxidant activity of ebselen and related organoselenium compounds.	horseradish peroxidase (hrp) inhibition and glutathione peroxidase (gpx) activities of ebselen and some related derivatives are described. these studies show that ebselen and ebselen ditelluride (ebte(2)) with significant antioxidant activity, inhibit the hrp-catalyzed oxidation reactions. in addition, inhibition of lipid peroxidation and singlet oxygen quenching studies were carried out. although the inhibition of hrp by ebselen is comparable with that of ebte(2), the inhibitory effect on gamma ...	2006	16919452
hydroxyl-containing antimony oxide bromide nanorods combined with chitosan for biosensors.	a hydroxyl-containing antimony oxide bromide (aob) nanorods was synthesized by a hydrothermal method. tem and sem images showed that the as-prepared aob nanorods were very copious with diameters of about 50 nm. the aob nanorods could be easily combined with biopolymer chitosan (chi) to form an organic-inorganic hybrid material, and a biocompatible, crack-free and porous chi-aob composite film could be readily obtained. horseradish peroxidase (hrp) was chosen as a model protein to construct a rea ...	2006	16901539
protonation and hydrogen-bonding state of the distal histidine in the co complex of horseradish peroxidase as studied by ultraviolet resonance raman spectroscopy.	ultraviolet resonance raman (uvrr) spectroscopy has been used to characterize the structure and hydrogen bonding state of the distal histidine (his42) in horseradish peroxidase (hrp) complexed with carbon monoxide (hrp-co). the hrp-co - hrp uvrr difference spectrum in d(2)o solution at pd 7.0 shows two positive peaks at 1408 and 1388 cm(-)(1), which are ascribable to medium-to-weak and strong hydrogen bonding states, respectively, of the protonated imidazolium side chain of his42 in hrp-co. both ...	2006	16893167
microsphere-based bioresorbable structures loaded with proteins for tissue regeneration applications.	novel bioresorbable fiber/microsphere composite structures loaded with proteins were developed and studied. these unique polymeric structures are designed to combine good mechanical properties with a desired controlled protein-release profile, in order to serve as scaffolds for tissue regeneration applications. the composite fiber structures were formed by "coating" poly(l-lactic acid) fibers with protein-containing poly(dl-lactic-co-glycolic acid) microspheres. the microspheres were prepared by ...	2006	16883585
novel bioresorbabale composite fiber structures loaded with proteins for tissue regeneration applications: microstructure and protein release.	novel bioresorbable core/shell composite fiber structures loaded with proteins were developed and studied. these unique polymeric structures are designed to combine good mechanical properties with a desired controlled protein-release profile, to serve as scaffolds for tissue regeneration applications. core/shell fiber structures were formed by "coating" poly(l-lactic acid) fibers with protein-containing poly(dl-lactic-co-glycolic acid) porous structures. shell preparation (coating) was performed ...	2006	16883584
natural and synthetic hormone removal using the horseradish peroxidase enzyme: temperature and ph effects.	the primary objective of our research was to establish the technical feasibility of using the horseradish peroxidase (hrp) enzyme for natural and synthetic estrogens-estrone (e1), 17beta-estradiol (e2), estriol (e3), and 17alpha-ethinylestradiol (ee2)-removal. the effects of temperature and ph on enzymatic treatment kinetics were investigated. residual estrogen concentrations were quantified by liquid chromatography, coupled with mass spectrometry analysis. in a synthetic solution at ph 7 and 25 ...	2006	16849026
nanosecond responses of proteins to ultra-high temperature pulses.	observations of fast unfolding events in proteins are typically restricted to <100 degrees c. we use a novel apparatus to heat and cool enzymes within tens of nanoseconds to temperatures well in excess of the boiling point. the nanosecond temperature spikes are too fast to allow water to boil but can affect protein function. spikes of 174 degrees c for catalase and approximately 290 degrees c for horseradish peroxidase are required to produce irreversible loss of enzyme activity. similar tempera ...	2006	16844754
kinetic analysis of semisynthetic peroxidase enzymes containing a covalent dna-heme adduct as the cofactor.	the reconstitution of apo enzymes with dna oligonucleotide-modified heme (protoporphyrin ix) cofactors has been employed as a tool to produce artificial enzymes that can be specifically immobilized at the solid surfaces. to this end, covalent heme-dna adducts were synthesized and subsequently used in the reconstitution of apo myoglobin (amb) and apo horseradish peroxidase (ahrp). the reconstitution produced catalytically active enzymes that contained one or two dna oligomers coupled to the enzym ...	2006	16832798
flavin-containing polyamine oxidase is a hydrogen peroxide source in the oxidative response to the protein phosphatase inhibitor cantharidin in zea mays l.	in this study, the specific contribution of polyamine oxidase (pao), a hydrogen peroxide (h2o2)-producing enzyme, to the oxidative burst induced in maize mesocotyl by the phosphatase inhibitor cantharidin was examined. for this purpose, a pharmacological approach was applied using, either in vitro or in vivo, two strong inhibitors of maize pao (mpao), n-prenylagmatine (g3) and its structural analogue ro5, as well as diphenyleneiodonium (dpi), an inhibitor of the phagocyte nad(p)h oxidase. dpi wa ...	2006	16831849
absorption detection of enzymatic reaction using optical microfluidics based intermittent flow microreactor system.	the advantages of integrating microfluidics into photonics-based biosensing for fabricating microreactor type lab-on-a-chip devices carries a lot of advantages, such as smaller sample volume handling, controlled drug delivery and high throughput diagnosis, which is useful for in situ medical diagnosis and point-of-care (poc) testing. a hybrid integrated optical microfluidic system has been developed for the study of single molecules and enzymatic reactions. the method of optical absorption has b ...	2006	17187445
using novel polysaccharide-silica hybrid material to construct an amperometric biosensor for hydrogen peroxide.	a new type of sol-gel organic-inorganic hybrid material was developed and used for the fabrication of an amperometric hydrogen peroxide biosensor. this material was prepared from natural chitosan and recently introduced completely water-soluble precursor, tetrakis(2-hydroxyethyl) orthosilicates (theos), by the sol-gel process without the addition of organic solvents and catalysts. the gelation time for the sol-gel transition and dynamic rheological properties of the resultant gel matrix could be ...	2006	17149906
cyclic voltammetric responses of horseradish peroxidase multilayers on electrodes.	the catalytic responses obtained with step-by-step neutravidin-biotin deposition of successive monolayers of hrp are analyzed by means of cyclic voltammetry. the theoretical tools that have been developed allowed full characterization of the multilayered hrp coatings by means of a combination between closed-form analysis of limiting behaviors and finite difference numerical computations. an analysis of the experiments in which the number of monolayers was extended to 16 allowed an approximate de ...	2006	17129064
embryonic development of pleuropodia of the cicada, magicicada cassini.	in many insects the first abdominal segment possesses embryonic appendages called pleuropodia. here we show the embryogenesis of pleuropodial cells of the periodical cicada, magicicada cassini (fisher 1851) (insecta, homoptera, cicadidae). an antibody, anti-horseradish perioxidase (hrp), that is usually neuron-specific strongly marked the pleuropodial anlagen and revealed their ectodermal origin shortly after limb bud formation. thereafter the cells sank into the epidermis and their apical parts ...	2006	19537987
rapid and efficient enzyme encapsulation in a dendrimer silica nanocomposite.	we report the entrapment of horseradish peroxidase and quantitative encapsulation of glucose oxidase within silica nanoparticles by utilizing an amine-terminated dendritic template. our improved strategy employs a water-soluble biomimetic template which is able to catalyze the condensation of si(oh)(4) to silica nanoparticles while trapping an enzyme inside the mesoporous material. kinetic analysis shows enzyme functionality to be mostly unchanged. also, the role of pi and ionic strength within ...	2006	17039576
a europium(iii) complex as an efficient singlet oxygen luminescence probe.	a new europium(iii) complex, [4'-(10-methyl-9-anthryl)-2,2':6',2"-terpyridine-6,6"-diyl]bis(methylenenitrilo) tetrakis(acetate)-eu(3+), was designed and synthesized as a highly sensitive and selective time-gated luminescence probe for singlet oxygen ((1)o2). the new probe is highly water soluble with a large stability constant of approximately 10(21) and a wide ph available range (ph 3-10), and can specifically react with (1)o2 to form its endoperoxide (ep-mtta-eu(3+)) with a high reaction rate ...	2006	17031957
purification and thermal characterization of a novel peroxidase from a local chick pea cultivar.	a novel peroxidase isolated from a local chick pea (cicer arietinum l.) cultivar (balksar 2000) was purified by means of ammonium sulfate precipitation, deae-cellulose chromatography and two runs on gel filtration. the purified enzyme has a specific activity of 2045 u/mg with 17 % activity recovery. the molecular mass of the enzyme was estimated to be 39 kda by sds-polyacrylamide gel electrophoresis. optimum ph and temperature of the enzyme were 5.5 and 45 degrees c respectively. the thermal den ...	2006	17073725
elementary steps of enzymatic oxidation of nifedipine catalyzed by horseradish peroxidase.	the elementary steps of the enzymatic oxidation of nifedipine (nf) catalyzed by horseradish peroxidase (hrp) have been described based on analysis of kinetic magnetic field effects (mfes). it has been shown that the first step of the catalytic cycle is single electron transfer resulting in formation of nf*(+) radical cation and ferroperoxidase (per(2+)). as a result, comparison with an earlier studied oxidation reaction of nadh catalyzed by hrp evidenced that the enzymatic oxidations of two subs ...	2006	17048950
can the replacement of a single atom in the enzyme horseradish peroxidase convert it into a monoxygenase? a density functional study.	density functional calculations on horseradish peroxidase mutants are presented, whereby one or two of the nitrogen atoms of the axial histidine ligand have been replaced by phosphorus atoms. our calculations show that phosphorus entices a push effect on the oxoiron group, whereas a histidine side chain withdraws electrons. as a result, we predict that a phosphorus-substituted histidine ligand will convert the active form of a peroxidase into a monoxygenase. this subsitution may be useful for th ...	2006	17048883
picomolar peroxide detection using a chemically activated redox mediator and square wave voltammetry.	a method for low-level, low-potential electrochemical detection of hydrogen peroxide using a chemically activated redox mediator is presented. this method is unique in that it utilizes a mediator, amplex red, which is only redox-active when chemically oxidized by h2o2 in the presence of the enzyme horseradish peroxidase (hrp). when employed in concert with microelectrode square wave voltammetry to optimize sensing at ultralow concentrations (<1 microm), this method exhibits marked improvements i ...	2006	17165848