bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical biosensors for inhibitor determination: Selectivity and sensitivity control
Authors: Budnikov Herman C. , Evtugyn Gennady A. 
Published: May 2005

AbstractThe behavior of cholinesterase based potentiometric and amperometric biosensors with renewable membranes toward irreversible inhibitor determination has been investigated. Tracing paper, gelatin and cellulose nitrate were examined, as membrane materials. The membranes are replaced in the biosensor assembly after 15–20 inhibition measurements. The detection limits as well as other analytical characteristics of inhibitor determination for different enzyme supports and detection systems are compared and discussed.
Sonoelectrochemical processes: A review
Authors: Compton Richard G. , Eklund John C. , Marken Frank 
Published: May 2005

AbstractThe considerable progress made in the development of fundamental and applied aspects of sonoelectrochemistry, the coupling of power ultrasound into an electrochemical experiment, is reviewed with respect mainly to the measurement and analysis of effects observed in conventional sonoelectrochemical experiments in homogeneous environments. Based on the tools and methods now available it is hoped that the application of ultrasound in areas as diverse as electroanalytical and synthetic electrochemistry will be beneficial and new innovative approaches employing the various mechanical and chemical effects of ultrasound will result.
Indirect voltammetric determination of lanthanides in the presence of mordant red 19
Authors: Lee Sang Kwon , Chung Tack Dong , Kim Hasuck 
Published: May 2005

AbstractComplexes of lanthanide with Mordant Red 19 (MR19) are shown to be adsorbed and can be electrochemically reduced at mercury electrodes at a more negative potential than where MR19 is reduced. Based on these properties, an analytical application for the determination of lanthanides is demonstrated by linear sweep voltammetry (LSV) and by highly sensitive adsorptive stripping voltammetry (AdSV). By applying AdSV, the detection limit of several lanthanides is about 5.0 × 10−10 M with an accumulation time of 5 min and the linear response range is from 5.0 × 10−8 M to 1.0 × 10−6 M. A typical relative standard deviation is found to be 5.2% at the 5.0 × 10−8 M level. The results from LSV show that the difference in peak potentials (δEp) between complex and MR19 increases when the atomic number of lanthanide ion is increased. Because the smallest δEp due to the presence of La3+ is still large enough to distinguish the complex peak from dye peak, it is possible to recognize all members of lanthanide ions selectively with MR19, regardless of whether they are light or heavy ones. It is also possible to perform simultaneous analysis for some mixtures. In addition, the range of lanthanide concentration, for which quantitative analysis is valid, becomes wider as a result of using LSV as well as AdSV.
Layer‐layer assembly for extremely stable glucose sensors
Authors: Khan Golam Faruque 
Published: May 2005

AbstractA novel fabrication of an amperometric glucose sensor by layer after layer approach is described. The sensor electrode is fabricated by arranging a layer of Pt black, a layer of glucose oxidase (GOD) and a layer of stabilizer gelatin on a shapable electro‐conductive (SEC) film surface. Finally, the dried layered‐assembly is cross‐linked by exposing to a diluted glutaraldehyde solution. The performance of the developed sensor is evaluated by a FIA system at 37°C and under a continuous polarization at 0.4 V (vs. Ag/AgCl). The sensitivity of the sensor was dependent on the amount of GOD loaded. The highest sensitivity (3.6 μA/mM cm−2) of the sensor was obtained at a GOD loading of 160 μg/cm2, and the linear dynamic range was extended to 80 mM level when the sensor was covered with a polycarbonate membrane. The sensor shows an extremely stable response for several weeks and a storage stability of over 2 years.
Flow injection, amperometric determination of ethanol in wines after solid‐phase extraction
Authors: Chen Zuliang , Yu Ji Jin , Hibbert D. Brynn 
Published: May 2005

AbstractEthanol in wines was determined by flow injection analysis with an amperometric detector using an oxidized nickel wire. Solid‐phase extraction with a strong anion exchanger was used to remove interferences such as organic acids from the matrix, and the residue of the extraction was injected directly into the FIA system. The recoveries of ethanol from wines spiked with standards ranged from 101% to 103%. The response of the nickel electrode to ethanol is dependent on the applied potential and the pH of the carrier. The optimal conditions for the detection of ethanol were an applied potential of +0.60 V (vs. Ag/AgCl) in a carrier of 100 mM sodium hydroxide solution. The electrode exhibited a linear response from 10−5 to 10−3 M, with a detection limit of 1 × 10−6 M. The method was demonstrated by the determination of ethanol in wines.
Coulometric stripping potentiometry for arsenic(III)
Authors: Ratana‐ohpas Roongroje , Jagner Daniel , Ma Feng 
Published: May 2005

AbstractCalibration‐free determination of AsIII in the presence of AsV using coulometric stripping potentiometry is described. AsIII, in the concentration range 0.01‐2 mg/L, is quantitatively reduced to elemental arsenic and simultaneously dissolved in gold codeposited onto a glassy carbon substrate by electrolysis for 4 minutes at −0.50 V (vs. Ag/AgCl (0.01 MCl−)) in 12 μL samples containing 3 M hydrochloric acid and 10 mg/L gold(III). Selectivity between arsenic(III) and (V) is achieved by proper control of the deposition potential and by minimizing the gold(III) concentration and the time between addition of gold(III) and commencement of analysis.
Determination of chloride by stripping chronopotentiometry with silver‐film electrode
Authors: Suturović Zvonimir J. , Marjanović Nikola J. , Dokić Petar P. 
Published: May 2005

AbstractThe experimental parameters of cathodic stripping chronopotentiometry of chloride at a silver‐film electrode are investigated and optimized. The chloride preconcentration is achieved in the form of silver chloride by a controlled potential oxidation of the working electrode under vigorous stirring. Cathodic stripping of the deposit is obtained by the constant current, under the condition of diffusive mass transfer. Deaeration of the solution is not necessary. A detection limit of 35 μ dm−3 (10−6 mol dm−3) is obtained at a deposition time of 180 s, with a reproducibility of 6.7 % (expressed as relative standard deviation, RSD).
Determination of dissociation constants by affinity electrophoresis: Complexes between human serum proteins and concanavalin A
Authors: Bøg‐Hansen Thorkild C. , Takeo Kazusuke 
Published: May 2005

AbstractThe general equation for determination of dissociation constants by affinity electrophoresis is given. Dissociation constants of macromolecular complexes may be determined irrespectively of the mobility of the complex. Complexes between two macromolecular components may be studies. Dissociation constants are given for concanavalin A‐complexes of human serum proteins: two components of alpha1‐antitrypsin, two components of orosomucoid (alpha1‐acid glycoprotein), high density lipoprotein‐associated arylesterase, haptoglobin, alpha2‐HS‐glycoprotein, and transferrin. When the affinity electrophoresis is performed as lectin interaction electroimmuno precipitation (crossed immunoelectrophoresis with lectin in the first dimension gel) prior purification is unnecessary.
A new technique for eluting proteins from polyacrylamide gels: Flat‐bed electrophoretic elution in Sephadex via isoelectric focusing
Authors: Lasky Marvin , Manrique Albert 
Published: May 2005

AbstractWe have developed a new technique, flat‐bed electrophoretic elution in Sephadex via isolectric focusing for the removal of proteins from polyacrylamide gels subsequent to electrophoresis. A narrow slice of the polyacrylamide gel, which contains the protein to be eluted, is finely ground and applied to a horizonatal bed of Sephadex G‐200 SF containing carrier ampholytes. Upon focusing the Sephadex plate, the protein rapidly elutes and migrates to its isoelectric point where it bands and concentrates. This method, by circumventing many of the problems and limitations of current elution methods and apparatus, ensures the recovery of proteins in concentrated form with a high yield.Conditions for optimal rates of elution were developed. For best results, a finely chopped slice of the gel, which contains the protein, is mixed in with some of the Sephadex G‐200 SF which has been removed from a narrow rectangular application zone of a flat‐bed plate. The application zone is chosen several pH units from the isoelectric point of the eluting material. The use of a broad pH carrier ampholyte in the bed generally proves superior to a narrow range interval. High voltage can be used due to the excellent cooling capacity of the system and the even conductivity of the Pharmalyte® carrier ampholytes. The technique is relatively mild and should only minimally influence the biological activity of the eluted material.
Determination of protein‐ligand dissociation constants of their pH dependence by combined isoelectric focusing‐electrophoresis (titration curves): Binding of phosphorylases a and b to glycogen
Authors: Ek Kristina , Righetti Pier Giorgio 
Published: May 2005

AbstractAffino‐titration curves, a variant of conventional affino‐electrophoresis techniques, allow the simultaneous determination of protein‐ligand dissociation constants (Kd) and of their pH‐dependence in the pH range 3–10. If the ligand is a macromolecule, it is simply entrapped in the gel matrix; if it is a small molecule, it is covalently bound to the gel fibers. When a titration curve of a protein is run in presence of increasing amounts of ligand in the gel, the progressively decreasing mobilities, when plotted against the ligand molarity in the gel, can be used to calculate Kd's at any pH value. This technique has been used to measure the dissociation constants of glycogen with phosphorylases a and b, and their pH‐dependence.
Natural pH gradients formed by two and three aminoacids on polyacrylamide gel: Changes of pH, segmental voltages and aminoacid distributions with time
Authors: Jackiw B. Andrew , Chrambach Andreas 
Published: May 2005

AbstractA natural pH gradient can be formed on polyacrylamide gel using either two (glutamic acid and lysine only) or three (glutamic acid, histidine and lysine) aminoacids as the sole carrier ampholyte species. In the two component system, glutamic acid and lysine focus as single peaks adjacent (anodically and cathodically, respectively) to the steep, linear center of the step‐function pH gradient. Histidine, in the three component system, focuses at the center of the pH gradient and separates the other two aminoacids. Each aminoacid electrofocuses at its pI. Hemoglobin electrofocuses as a sharp band in both systems and, in the two component system, remains focused at its pI for 200 h. A major conductance gap forms at the gel center in both systems with progressing time of electrofocusing; a minor and transient conductance gap develops in the glass tube just above the gel.
The analysis of the proteins of heterogeneous ribonucleoprotein particles on two‐dimensional polyacrylamide gels
Authors: Wilks Andrew F. , Knowler John T. 
Published: May 2005

AbstractMethods of two‐dimensional protein fractionation have been analysed for their suitability for the analysis of heterogeneous ribonucleoprotein (hnRNP) particles. Nonequilibrium pH gradient electrophoresis gives the best overall fractionation and reveals that the dominant “core” proteins possess charge heterogeneity. For the analysis of the minor components of the particles, it may be preferable to overload isoelectric focusing gels and allow the basic core proteins, which comprise 70% of the total protein, to migrate off the gel. This does, however, result in the loss of some basic minor polypeptides.
The “betagram” for rapid localization of 3H‐labeled proteins in SDS polyacrylamide gels
Authors: Kruppa Joachim , Bauche Andreas 
Published: May 2005

AbstractThe distribution pattern of 3H‐labeled proteins in slab gels has been recorded with two instruments: a thin‐layer scanner and a Betacamera, both of which have been used with success previously in monitoring paper and thin‐layer chromatograms. Individual radioactive protein bands may be localized with both instruments although they differ markedly in sensitivity. The scanner is relatively insensitive and thus time‐consuming, since each lane of the gel has to be recorded separately. In contrast, with the Betacamera the whole area of the slab gel could be monitored simultaneously. The extraordinarily high sensitivity of the Betacamera in detecting 3H‐compounds via the spark chamber proved to be of great advantage since we intended to isolate preparatively specific proteins from the gel. The “betagram” technique has a very low detection limit and is thus less time‐consuming than fluorography. However, the resolution of the “betagram” is limited due to the number of wires in the spark chamber, and does not reach the quality attained with fluorography.
Amplified immunoperoxidase staining of isoelectrically focused human tumor markers
Authors: Saravis Calvin A. , Cantarow Walter , Marasco Patrick V. , Burke Bohdana , Zamcheck Norman 
Published: May 2005

AbstractAvidin‐biotin amplified immunoperoxidase staining of the human tumor marker, carcinoembryonic antigen (CEA) localized in malignant tissue by isoelectric focusing is described. CEA either in electrofocused aqueous tissue extracts or extracted and separated by direct tissue isoelectric focusing in agarose (IsoGel), was reacted with rabbit and anti‐CEA antiserum and with enzyme conjugated swine anti‐rabbit antiserum, or with avidin‐biotin conjugated reagents, then with enzyme substrate. Avidin‐biotin amplified immunoperoxidase staining of CEA gave more intense staining. Quantitation and characterization of tumor markers by direct tissue electrophoresis in isoelectric focusing media and enzyme amplification of anti‐tumor marker antisera, make possible the study of their biological meaning and clinical usefulness.
Two‐dimensional micro‐electrophoresis of proteins from plant‐parasitic nematodes: Increased sensitivity of protein detection by silver staining or in vivo labeling
Authors: Poehlingss Hans‐Michael , Wyss Urs , Neuhoff Volker 
Published: May 2005

AbstractMinimal amounts of proteins from plant‐parasitic nematodes are sufficient for separation in two‐dimensional micro‐electrophoresis with high resolution. It can be shown that the host – parasite interaction leads to a drastic change of the protein composition in the parasite. Silver staining or in vivo labeling of the nematode proteins results in an increased sensitivity of protein detection.
Demonstation of human prealbumin by double one‐dimensional slab gel electrophoresis
Authors: Altland Klaud , Rauh Silke , Hackler Rolf 
Published: May 2005

AbstractA double one‐dimensional (D 1‐D) electrophoretic method for slab gels with polyacrylamide gel electrophoresis (PAGE) followed by polyacrylamide gel isoelectric focusing (PAGIF) is described for the demonstration of prealbumin (PA) from human sera. Almost pure PA is obtained when serum is submitted to Page i an anionic discontinuous (glycine‐chloride) buffer system at alkaline pH. After page the Bromophenol Blue‐stained tracking dye boundary in the gel containing PA is cut out and the gel strips are overlayed on an isoelectric focusing gel. A final PAGIF pattern of PA is obtained which is hidden by other serum proteins when one‐dimensional PAGIF is performed. PAGIF of PA in a gel containing a gradient from 0 to 8 M urea perpendicular to the pH axis reveals the conversion of at least 7 diffuse bands with isoelectric point (pI) values between 4.2 and 4.7 into three sharp zones with pI values of 5.45 for one minor zone and 5.7 for the two other zones lying very close together. Among 1900 sera from adult pregnant women, 2 were found containing a genetically determined PA variant with a pI of 5.9 for a minor and a pI of 6.35 for a more intense zone in addition to the usual pattern. From the variant PAGE and PAGIF patterns and their distribution in the families of the carriers, it is concluded that PA is a tetramer under control of an autosomal structural gene which remains stable during PAGE abut dissociates into the monomers during PAGIF in the presence or presence of urea it is followed that PA under physiological conditions possibly forms complexes with more components than expected from its known binding capacity for thyroxine and retinal binding protein (RBP). This highly resolving K 1‐D electrophoretic technique allows the simultaneous analysis of up to 96 samples under identical experimental conditions. It is concluded that PA may be a good candidate for human mutation monitoring at the protein level.
The use of carbamylated charge standards for testing batches of ampholytes used in two‐ dimensional electrophoresis
Authors: Tollaksen Sandra L. , Edwards Jesse J. , Anderson Norman G. 
Published: May 2005

AbstractA method of testing batches of ampholytes is presented. By using carbamylated charges standards to co‐electrophorese with the protein sample in the first‐dimension isoelectric focusing gel, one can monitor, after running and staining the second‐dimension sodium dodecyl sulfate (SDS) slabs gel, the continuity of the pH gradient. Charge standards can also be used to check the reproducibility of the pH gradient among batches of ampholytes and to modify the new batch with a small amount of a narrow range ampholyte to assure reproducibility of experiments. Ampholytes for comparison were obtained from three major manufacturers.
Toward an improved immunoglobulin analysis by gel electrophoresis and electrofocusing
Authors: Chrambach Andreas , Lan Birgit An Der , Mohrmann Helga , Felgenhauer Klaus 
Published: May 2005

AbstractThe analysis of immunoglobulin by gel electrophoretic methods is presently burdened with two problems: the incapacity of conventional buffer systems to spread the polyclonal immunoglobulin pattern across the entire separation path length in gel electrophoresis, and the appearance of distinct bands in the conventional electrofocusing patterns, instead of he continuum of zones — which would be expected form a polyclonal mixture of “charge isomers” and which is indeed obtained in gel electrophoresis. Polyclonal serum immunoglobulin differ from one another predominantly in net charge (i.e., they are “charge isomers”). The operative pH of gel electrophoresis was therefore optimized. The acidic side of he isoelectric operative pH of 5.32, a discontinuous (multiphase) buffer system was found which was capable of stacking all immunoglobulin in a lyophilized preparation.In order to provide a magnified view immunoglobulin heterogeneity, the immunoglobulin mixture was fractionated into 26 groups of charge isomers using preparative isotachophoresis. When subjected to polyacrylamide gel electrophoresis in resolving gels operative at pH 4.85, 0°C, the isotachophoretic fractions spread between relative mobility values of 0.4 to 0.9 in the electrophoresis pattern, i.e., their sum total covered the entire separation path. Under these conditions, isotachophoretic fractions also revealed immunoglobulin oligomers. The number of oligomeric forms increased from increased from the leading (most basic) to the trailing (most acidic) immunoglobulin components within the stack.In polyacrylamide gel electrofocusing of the isotachophoretic fractions of immunoglobulin, using pI‐renge 6–9 ampholine, addition of a 0.01 M mixture of amino acids to the carrier ampholytes, and 20h or more electrofocusing time at 20 V/cm of gel, 0°C, polyclonal immunoglobulin patterns appeared continuous. Electrofocusing patterns of those isotachophoretic fractions of immunoglobulin which contained oilgomeric forms (as revealed by gel electrophoresis ) exhibited one or two major bands against the continuous background of stainable components. Monoclonal immunoglobulin produced distinct major bands under the same comditions.Thus, either polyacrylamide gel electrofocusing in the pI‐range 6–9 or polyacrylamide gel electrophoresis in a buffer system operative at pH 4.85 appear promising for the development of a clinically practical and artifact‐free electrophoresis analysis for specific oligoclonal immunoglobulin.
Agarose‐Sephadex: A new improved matrix for preparative flatbed isoelectric focusing
Authors: Manrique Albert , Lasky Marvin 
Published: May 2005

AbstractA new, simple procedure is described for the preparation gel matrix for preparativde isolelectic focusing (IEF). 0.5–1% Agarose of IEF grade is incorporated with 2.5% Sephadex G‐200 Superfine (SF) and 3% Pharmalyte, yielding a uniform and rifid m atirx. No gel washing, swelling of degassing is necessary. Optimum gel consistency is quickly and easily obtained since no dehydration of the gel timum gel consistency is quickly and easily obtained since no dehydration of the gel slurry is required. Gel preparation time is reduced to 0.5–1 h and gel handling is simplified. Protein can be easily recovered from the matrix. The pH gradient profile and resolving properties of agarose‐Sephadex were compared with those of Spphdex G200 SF and IEF‐grade agarose. The profiles of agarose‐Sephadex and Sephadex matrixes are smoother and extend further in both directions than those for agarose. Focusing in agarose‐Sephadex and Sephadex also results in fewer edge effects. The ability to distinguish closely resolved bands in agarose‐Sephadex is superior due to its ability to be directly stained and its avoidance of eletroen‐domestic effects associated with focusing in sgarose. Changes in voltages enables us to follow the development, stability, and decay of the pH gradient. Agarose‐Sephadex and Sephadex pH gradients developed more smoothly and remained more stable than those for agarose. This new support system combines the good focusing properties of Sephades G‐200 SF with the simple handling, rapid and uniform gel formation of agarose, while overcoming many of the drawbacks of using either material alone.
Agarose gel electrophoresis of bacteriophages and related particles. II. Correction of electrophoretic mobilities for the electro‐osmosis of agarose
Authors: Serwer Philip , Hayes Shirley J. 
Published: May 2005

AbstractBacteriophage T4, bacteriophage T4 without its tail fibers, and bacteriophage P22 without its tail have been subjected to electrophoresis in agarose gels; electrophoretic mobility (μ) of these particles as a function of the concentration of agarose (A) has been determined using preparations of agarose with different amounts of electro‐osmosis. When μ was extrapolated to an A of 0 (μo), it was found that a term, μE, constant for each preparation of agarose must be added to μo to correct for electro‐osmotic flow. A relationship between μE and a manufacturer‐determined coefficient of electro‐osmosis has been empirically derived. Corrected μo's are in agreement with data obtained by solid support‐free electrophoresis.
Periodic acid‐Schiff staining of type II collagen and its cyanogen bromide peptides after polyacrylamide gel electrophoresis
Authors: Rajan Jess C. , Klein Leroy 
Published: May 2005

AbstractPepsin‐solubilized type II collagen and some of its CNBr‐derived peptides could be stained for carbohydrate with periodic acid‐Schiff (PAS) after polyacrylamide gel electrophoresis. PAS intensely stained an aldehyde‐containing peptide (Mr > 10 000) which was not detected with Coomassie Brilliant Blue R‐250 stain. Types I and III collagens and their CNBr peptides stained poorly, if at all, with PAS.