bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of high‐mannose‐type oligosaccharides by microliquid chromatography‐mass spectrometry and capillary electrophoresis
Authors: Koller Antonius , Khandurina Julia , Li Jincai , Kreps Joel , Schieltz David , Guttman András 
Published: June 2004

AbstractWe report on microbore liquid chromatography (μLC) and capillary electrophoresis (CE) separation of glycopeptides and high‐mannose‐type oligosaccharides, digested from recombinant phospholipase C, expressed in Pichia pastoris. The glycopeptides were subject to μLC/electrospray ionization/mass spectrometry (ESI‐MS) and μLC/ESI‐tandem MS (MS/MS) analysis that revealed high‐mannose structure size variation between Man7GlcNAc2 and Man14GlcNAc2. Then, high‐performance CE was applied to identify possible positional isomers of the high‐mannose structures. For the CE experiments, the oligosaccharides were released from the glycoproteins by peptide‐N‐glycosidase F and labeled with 1‐aminopyrene‐3,6,8‐trisulfonic acid (APTS). Excellent separation of the possible positional isomers was attained, suggesting one for Man9GlcNAc2, two for Man10GlcNAc2, three for Man11GlcNAc2, Man12GlcNAc2, and Man13GlcNAc2, and two for Man14GlcNAc2. The CE results provided complementary information to the μLC/ESI‐MS and MS/MS data with respect to the possible number of positional isomers.
Application of capillary electrophoresis‐mass spectrometry to synthetic in vitro glycolysis studies
Authors: Itoh Aya , Ohashi Yoshiaki , Soga Tomoyoshi , Mori Hirotada , Nishioka Takaaki , Tomita Masaru 
Published: June 2004

AbstractWe propose an approach designed to reconstitute a metabolic pathway composed of multistep biochemical reactions, rather than to dissect the individual reactions that make up the pathway. A synthetic in vitro glycolysis was reconstructed from ten purified Escherichia coli (E. coli) enzymes to obtain a better understanding of the regulation of sequential enzymatic reactions. The key to the success of this approach is the ability to perform direct and simultaneous determination of the diverse metabolic intermediates in the pathway by capillary electrophoresis‐mass spectrometry. We observed that the pathway is regulated by a delicate balance between the changing metabolite concentrations and behaves like a natural biological oscillating network that has hitherto not been reported for E. coli glycolysis. The end‐product, pyruvate, was periodically synthesized from glucose at an overall efficiency of 30%, corresponding to an average of 90% conversion efficiency for each of the ten steps involved. This approach is likely useful for the synthesis of natural products requiring complex sequential biocatalytic reactions.
Application of capillary electrophoresis/ electrospray ionization‐mass spectrometry to subcellular proteomics of Escherichia coli ribosomal proteins
Authors: Moini Mehdi , Huang Hsiaoling 
Published: June 2004

AbstractWe introduce capillary electrophoresis‐mass spectrometry (CE‐MS) as an efficient means for the on‐line separation and identification of protein mixtures. It was found that while CE/electrospray ionization (ESI)‐MS analysis of whole‐cell lysate was too complicated for the one‐dimensional CE‐MS analysis, the technique was useful for the analysis of protein mixtures of moderate complexity (∼50 intact proteins). CE/ESI‐MS was applied to the subcellular proteomics of ribosomal Escherichia coli. 55 out of the 56 ribosomal proteins were detected with ease by using only ∼3.4 ng of ribosomal proteins. In addition, it was found that the mass accuracy of the conventional MS (such as quadrupole ion traps) was good enough to identify many post‐translational modifications of the intact proteins by simply comparing their measured average molecular weight with the average molecular weight predicted from gene banks.
State‐of‐the‐art of the hyphenation of capillary electrochromatography with mass spectrometry
Authors: Barceló‐Barrachina Elena , Moyano Encarnación , Galceran M. Teresa 
Published: June 2004

AbstractThe high separation efficiency and loading capacity of capillary electrochromatography (CEC) make it an attractive separation mode for coupling with mass spectrometry (MS), which has the ability to unambiguously identify analytes with high selectivity and sensitivity. We present an overview of recent advances on both instrumentation and separation columns employed in CEC‐MS systems. In particular, the main characteristics of the stationary phases, as well as the configurations of the column outlet that are related with the coupling arrangements of the MS ionization sources, are reported. At present, packed columns and conventional electrospray ionization (ESI) sources are mainly employed in CEC‐MS. Nevertheless, the use of monolithic capillary columns and nanoelectrospray sources has the potential for wide acceptance in the next future. Moreover, the main features of several mass analyzers including ion trap, quadrupole, time‐of‐flight, magnetic sector, and Fourier transform‐ion cyclotron resonance are examined. Finally, current applications of this technology, mainly in the pharmaceutical field and proteomics, are reviewed.
Characterization of glyco isoforms in plasmaderived human antithrombin by on‐line capillary zone electrophoresis‐electrospray ionization‐quadrupole ion trap‐mass spectrometry of the intact glycoproteins
Authors: Demelbauer Uwe M. , Plematl Alexander , Kremser Leopold , Allmaier Günter , Josic Djuro , Rizzi Andreas 
Published: June 2004

AbstractThe carbohydrate structures of five isoforms of α‐AT and two isoforms of β‐AT were determined by applying capillary zone electrophoresis (CZE) on‐line coupled to electrospray ionization‐mass spectrometry (ESI‐MS) using an ion‐trap analyzer. For the AT preparations gained from a plasma pool at least semiquantitative information on the isoform‐distributions could be gained. Unlike to the commonly used approaches starting from enzymatically treated glycoproteins, this approach deals with intact proteins. The high accuracy of the molecular mass determination obtained by the ion‐trap analyzer allows one to calculate and ascertain the carbohydrate composition assuming no variations in the protein moiety of AT and to exclude or confirm the presence of the potential post‐translational or other modifications. Therefore, the direct coupling of CZE with ESI‐MS does not only represent a fast alternative technique to two‐dimensional electrophoresis (2‐DE) but serves as a method which provides structural information complementary to that gained from peptide mapping methods.
A chemometric study of active parameters and their interaction effects in a nebulized sheath‐liquid electrospray interface for capillary electrophoresis‐mass spectrometry
Authors: Nilsson Sara L. , Bylund Dan , Jörntén‐Karlsson Magnus , Petersson Patrik , Markides Karin E. 
Published: June 2004

AbstractA chemometrics approach has been used for evaluating the effect of four experimental parameters when coupling capillary electrophoresis (CE) to electrospray ionization‐mass spectrometry (ESI‐MS). Electrospray voltage, sheath‐liquid flow rate, nebulizing gas flow rate, and spray needle position in respect to the MS orifice were varied according to a full factorial design. In addition to main effects, two interaction effects could be identified as significant when measuring the peak intensity of the analytes, from a sample mixture containing peptides and pharmaceuticals. The first interaction effects, between the nebulizing gas flow rate and the sheath‐liquid flow rate, and the second interaction effect, between the nebulizing gas flow rate and the spray position, could further explain the impact that these variables have on the spray performance. The number of theoretical plates and the baseline noise were also measured. The sheath‐liquid flow was found to significantly affect the separation efficiency, while the noise level mainly was controlled by the nebulizing gas flow. The same factorial design was also used for a CE capillary with lower internal diameter (ID) and the effects of the same variables were compared on those capillaries using equal injection volume for both capillaries. Similar trends were obtained in both capillaries but capillary ID was shown to be a significant variable when evaluating both capillaries in a single model. It was found that a capillary with 25 μm ID provided improved CE‐MS performance over than corresponding 50 μm ID capillary. Enhanced sensitivity was obtained using the narrow‐bore capillary, and at lower sheath‐liquid flow rate the 25 μm ID capillary also gave rise to more efficient peaks.
Platinum metallodrug‐protein binding studies by capillary electrophoresis‐inductively coupled plasma‐mass spectrometry: Characterization of interactions between Pt(II) complexes and human serum albumin
Authors: Timerbaev Andrei R. , Aleksenko Svetlana S. , Polec‐Pawlak Kasia , Ruzik Rafal , Semenova Olga , Hartinger Christian G. , Oszwaldowski Slawomir , Galanski1 Mathea Sophia , Jarosz Maciej , Keppler Bernhard K. 
Published: June 2004

AbstractCharacterizing how platinum metallocomplexes bind to human serum albumin (HSA) is essential in evaluating anticancer drug candidates. Using cisplatin as a reference complex, the application of capillary electrophoresis (CE) to reliably assess drug/HSA interactions was validated. Since this complex is small compared to the size of the protein, the binding response could only be recognized when applying CE coupled to a (platinum) metal‐specific mode of detection, namely inductively coupled plasma‐mass spectrometry (ICP‐MS). This coupling allowed for confirmation of a specific affinity of cisplatin and novel Pt complexes to HSA, measurement of the kinetics of binding reactions, and determination of the number of drug molecules attached to the protein. As the cisplatin/HSA molar ratio increased, the reaction rate became faster with a maximum on the kinetic curve appearing at about 50 h of incubation at 20 times excess of cisplatin. The reaction was characterized as a pseudo‐first order reaction with the rate constant k = 0.003 min−1 at 37°C. When incubated with a 20‐fold excess of cisplatin, HSA bound up to 10 mol of Pt per mol of the protein. This is indicative for a strong metal‐protein coordination occurring at several HSA sites other than the only protein cysteine residue. Structural analogs of cisplatin, bearing aminoalcohol ligands, showed comparable protein binding reactivity and stoichiometry but a common equilibrium was not reached even after one week of incubation. Also apparent was a two‐step mechanism of the binding reaction. Results demonstrated the suitability of CE‐ICP‐MS as a rapid assay for high‐throughput studying of drug/HSA interactions.
Highly sensitive analysis of multiple pesticides in foods combining solid‐phase microextraction, capillary electrophoresis‐mass spectrometry, and chemometrics
Authors: Hernández‐Borges Javier , Rodríguez‐Delgado Miguel Á. , García‐Montelongo Francisco J. , Cifuentes Alejandro 
Published: June 2004

AbstractA highly sensitive procedure to detect multiple pesticides at trace levels in foods is presented. Initially a comparative study between capillary electrophoresis (CE)‐UV and CE‐mass spectrometry (MS) is carried out analyzing five pesticides not studied up to now (pyrimethanil, pyrifenox, cyprodinil, cyromazine, and pirimicarb). The comparison between CE‐UV and CE‐MS is established in terms of separation efficiency, speed of analysis, reproducibility, and sensitivity. A good separation of these compounds is achieved by both techniques using a volatile aqueous buffer containing 0.3 M ammonium acetate/acetic acid at pH 4. Time analysis reproducibility is studied for the same day (n = 5) and three different days (n = 15), showing no significant differences between CE‐UV and CE‐MS. The study on peak areas reproducibility shows a slightly worse reproducibility for CE‐MS compared with CE‐UV. The best limit of detection (LOD) that can be achieved for these pesticides using CE‐UV was 0.6 μg/mL. CE‐MS provides LODs one order of magnitude better than CE‐UV. Chemometrics are used to optimize the multiple parameters that play a role in solid‐phase microextraction (SPME) and CE‐MS analysis (e.g., extraction and desorption times, nebulizer pressure, dry gas flow, dry gas temperature, percentage of organic solvent and acid in the sheath liquid, etc.). The combined use of chemometrics and SPME‐CE‐MS clearly improves the LODs that can be achieved allowing the detection of pesticides at concentrations down to 15 ng/mL. The usefulness of this approach is demonstrated detecting multiple pesticides in different food samples as grapes and orange juice in a single run. The concentrations detected are below the maximum residue limits (MRLs) permitted for these pesticides in foods corroborating the value of our approach. This work demonstrates, to our knowledge for the first time, the good possibilities of the combined use of SPME‐CE‐MS and chemometrics.
Two‐dimensional liquid chromatography‐capillary zone electrophoresis‐sheathless electrospray ionization‐mass spectrometry: Evaluation for peptide analysis and protein identification
Authors: Janini George M. , Chan King C. , Conrads Thomas P. , Issaq Haleem J. , Veenstra Timothy D. 
Published: June 2004

AbstractA peptide separation strategy that combines two‐dimensional (2‐D) liquid chromatography (LC)‐capillary zone electrophoresis (CZE) with tandem mass spectrometry (MS/MS) is described for the identification of proteins in complex mixtures. To test the effectiveness of this strategy, a serum sample was depleted of the high‐abundance proteins by methanol precipitation, digested with trypsin to generate a complex peptide mixture, and separated into 96 fractions by reversed‐phase (RP)‐LC. Compared to ion‐exchange LC separations, RPLC provides much higher resolution and peak capacity. Fractions were collected off‐line from the RPLC separation, and subjected to short 20 min CZE separations. The separated zones were introduced to the mass spectrometer through a sheathless electrospray ionization interface that is integrated on the separation capillary. The ease of fabrication of the interface and its durability allowed for the analysis of all fractions on a single capillary in a relatively short analysis time. A stable electrospray was produced at nanoliter flowrates by augmenting analyte electrophoretic and electroosmotic mobilities with pressure‐assisted flow. Unlike first‐dimensional ion‐exchange LC fractionation, where there is a large degree of overlap, the CZE‐MS results show less than 15% overlap between neighboring RPLC fractions.
Detection of Amadori compounds by capillary electrophoresis coupled to tandem mass spectrometry
Authors: Hau Jörg , Devaud Stéphanie , Blank Imre 
Published: June 2004

AbstractCapillary electrophoresis coupled to mass spectrometry (CE‐MS) is reported for the first time as an alternative and powerful analytical method for the characterization and monitoring of N‐substituted 1‐amino‐1‐deoxyketoses (Amadori compounds). It allows rapid separation and identification of Amadori compounds, while benefiting from the well‐known advantages of MS, such as specificity and sensitivity. Amadori compounds of several amino acids, such as glycine, valine, isoleucine, methionine, proline, and phenylalanine, as well as a cysteine‐derived compound, were separated and/or discriminated using CE‐MS/MS under standard conditions. The technique may also be useful to study the stability and degradation kinetics of other labile charged Maillard intermediates that play an important role in food and medical science.
Pricing options using implied trees: Evidence from FTSE‐100 options
Authors: Lim Kian Guan , Zhi Da 
Published: June 2004

AbstractPreviously, few, if any, comparative tests of performance of Jackwerth's (1997) generalized binomial tree (GBT) and Derman and Kani (1994) implied volatility tree (IVT) models were done. In this paper, we
propose five different weight functions in GBT and test them empirically compared to both the
Black‐Scholes model and IVT.We use the daily settlement prices of FTSE‐100 index options from January to November 1999. With both
American and European options traded on the FTSE‐100 index, we construct both GBT and IVT from European
options and examine their performance in both the hedging of European option and the pricing of its American
counterpart. IVT is found to produce least hedging errors and best results for American call options with earlier
maturity than the maturity span of the implied trees. GBT appears to produce better results for American ATM put
pricing for any maturity, and better in‐sample fit for options with maturity equal to the maturity span of
the implied trees. Deltas calculated from IVT are consistently lower (higher) than Black‐Scholes
deltas for both European and American calls (puts) in absolute term. The reverse holds true for GBT
deltas. These empirical findings about the relative performance of GBT, IVT, and Standard Black‐Scholes
models are important to practitioners as they indicate that different methods should be used for different
applications, and some cautions should be exercised. © 2002 Wiley Periodicals, Inc. Jrl Fut Mark
22:601–626, 2002
What moves German Bund futures contracts on the Eurex?
Authors: Ahn Hee‐Joon , Cai Jun , Cheung Yan‐Leung 
Published: June 2004

AbstractThe German 10‐year Bund futures contract traded on the Eurex futures and options exchange in Frankfurt
became the world's most actively traded derivative product by the end of 1999. In this article, we provide a
detailed exploration of the interday and intraday return volatility in the Bund futures contract using a sample of
five‐min returns from 1997 to 1998. The evolution of interday volatility is described best by a
MA(1)‐fractionally integrated process that allows for the long‐memory features. At the
intraday level, we find that macroeconomic announcements from both Germany and the U.S. are an important source of
volatility. Among the various German announcements, we identify the IFO industry survey of business climate,
industrial production (preliminary), and Bundesbank policy meeting as being by far the most important.
The three most significant U.S. announcements include the employment report, the National Association of
Purchasing Managers (NAPM) survey, and employment costs. Overall, U.S. macroeconomic announcements have
a far greater impact on the Bund futures market than their German counterparts. © 2002 Wiley Periodicals,
Inc. Jrl Fut Mark 22:679–696, 2002
The Student Affairs Establishment and the Institutionalization of the Collegiate Ideal
Authors: Ortiz Anna M. 
Published: June 2004

AbstractThe traditional collegiate ideal is institutionalized on many campuses through the structure and the types of services offered by student affairs units. In order to change the collegiate ideal to represent a more inclusive environment, student affairs professionals must examine their policies and procedures and make changes that will help meet the developmental needs of nontraditional students.
Vocational Education and the Collegiate Ideal: The Threat and the Challenge of Limited Resources
Authors: Hagedorn Linda Serra 
Published: June 2004

AbstractAlthough fiscal restraints have impacted all levels of postsecondary education, community college vocational programs have been particularly hard hit. This chapter presents a thorough examination of present conditions, challenges the vision of “place,” and provides a realistic approach toward the “ideal” within vocational education community college programs.
Characterizing the spatial variability of groundwater quality using the entropy theory: II. Case study from Gaza Strip
Authors: Mogheir Y. , de Lima J. L. M. P. , Singh V. P. 
Published: June 2004

AbstractThis paper, the second in the series, uses the entropy theory to describe the spatial variability of groundwater quality data sets. The application of the entropy theory is illustrated using the chloride observations obtained from a network of groundwater quality monitoring wells in the Gaza Strip, Palestine. The application involves calculating information measures, such as transinformation, the information transfer index and the correlation coefficient. These measures are calculated using a discrete approach, in which contingency tables are used. An exponential decay fitting approach was applied to the discrete models. The analysis shows that transinformation, as a function of distance, can be represented by the exponential decay curve. It also indicates that, for the data used in this study, the transinformation model is superior to the correlation model for characterizing the spatial variability. Copyright © 2004 John Wiley & Sons, Ltd.
Transient modelling of lacustrine regressions: two case studies from the Andean Altiplano
Authors: Condom Thomas , Coudrain Anne , Dezetter Alain , Brunstein Daniel , Delclaux François , Jean‐Emmanuel Sicart 
Published: June 2004

AbstractA model was developed for estimating the delay between a change in climatic conditions and the corresponding fall of water level in large lakes. The input data include: rainfall, temperature, extraterrestrial radiation and astronomical mid‐month daylight hours. The model uses two empirical coefficients for computing the potential evaporation and one parameter for the soil capacity. The case studies are two subcatchments of the Altiplano (196 000 km2), in which the central low points are Lake Titicaca and a salar corresponding to the desiccation of the Tauca palaeolake. During the Holocene, the two catchments experienced a 100 m fall in water level corresponding to a decrease in water surface area of 3586 km2 and 55 000 km2, respectively. Under modern climatic conditions with a marked rainy season, the model allows simulation of water levels in good agreement with the observations: 3810 m a.s.l. for Lake Titicaca and lack of permanent wide ponds in the southern subcatchment. Simulations were carried out under different climatic conditions that might explain the Holocene fall in water level. Computed results show quite different behaviour for the two subcatchments. For the northern subcatchment, the time required for the 100 m fall in lake‐level ranges between 200 and 2000 years when, compared with the present conditions, (i) the rainfall is decreased by 15% (640 mm/year), or (ii) the temperature is increased by 5·5 °C, or (iii) rainfall is distributed equally over the year. For the southern subcatchment (Tauca palaeolake), the time required for a 100 m decrease in water level ranges between 50 and 100 years. This decrease requires precipitation values lower than 330 mm/year. Copyright © 2004 John Wiley & Sons, Ltd.