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  • 1
    Electronic Resource
    Electronic Resource
    A novel derivatization method for peptides to increase sensitivity and backbone fragmentation in liquid secondary-ion mass spectra (1992)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 6 (1992), S. 747-752 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Derivatization is used to increase both negative-ion sensitivity and positive-ion sequence information in the liquid secondary-ion mass spectra (LSIMS) of a series of peptides. The derivatization method involves acylation with pentafluorobenzyl fluoride in a single-step reaction, and the reaction mixture is applied directly to the probe tip for analysis. Acylation takes place at the unprotexted N-terminus, tyrosine, and lysine. The derivatives exhibit increased signal-to-noise ration for [M—H]- ions, especially where there is not already an acidic amino acid residue in the peptide. In positive-ion LSIMS, the N-terminal group acts to retain the charge at the N-terminus, simplifying the fragmentation by producing N-terminal fragment ions. It also increases positive-ion fragmentation, sometimes very dramatically, making sequence determination more straightforward. The simplicity of the process, together with the enhancements it provides, make3 this a generally useful method for obtaining peptide structural information.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290061207
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  • 2
    Electronic Resource
    Electronic Resource
    Actin-binding proteins regulate the work performed by myosin II motors on single actin filaments (1992)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 22 (1992), S. 274-280 
    Details
    ISSN: 0886-1544
    Keywords: motility assay ; gelation ; solation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Regulation of actin/myosin II force generation by calcium [Kamm and Stull, Annu. Rev. Physiol. 51:299-313, 1989] and phosphorylation of myosin II light chains [Sellers and Adelstein, “The Enzymes,” Vol. 18, Orlando, FL: Academic Press, 1987, pp. 381-418] is well established. However, additional regulation of actin/myosin II force generation/contraction may result from actin-binding proteins [Stossel et al., Ann. Rev. Cell Biol. 1:353-402, 1985; Pollard and Cooper, Ann. Rev. Biochem. 55:987-1035, 1986] as they affect the gel state of the actin cytomatrix [reviewed in Taylor and Condeelis, Int. Rev. Cytol., 56:57-143, 1979]. Regulation of the gel state of actin may determine whether an isotonic or isometric contraction results from the interaction between myosin and actin. We have extended the single actin filament motility assay of Kron and Spudich [Proc. Natl. Acad. Sci. U.S.A. 83:6272-6276, 1986] by including filamin or α-actinin on the substrate with myosin II to examine how actin-crosslinking proteins regulate the movements of single actin filaments. Increasing amounts of actin-crosslinking proteins inhibit filament velocity and decrease the number of filaments moving. Reversal of crosslinking yields increased velocities and numbers of moving filaments. These results support the solation-contraction coupling hypothesis [see Taylor and Fechheimer, Phil. Trans. Soc. London B 299:185-197, 1982] which proposes that increased crosslinking of actin inhibits myosin-based contraction. This study also illustrates the potentially varied roles of different actin-crosslinking proteins and offers a novel method to examine actin-binding protein activity and their regulation of motility at the single molecule level. © 1992 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970220407
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  • 3
    Electronic Resource
    Electronic Resource
    Tandem mass spectrometry of aminated fullerene derivatives (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 559-563 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The products of the reaction between fullerenes (C60/C70) and dimethylamine were investigated by fast atom bombardment (FAB) mass spectrometry and tandem mass spectrometry (MS/MS). The FAB mass spectrum shows peaks corresponding to the addition of up to eight dimethylamine species, exclusively to C70. MS/MS reveals an unusual fragmentation pattern. The mass spectrum of the reaction products, together with a number of tandem mass spectra, are shown.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210280515
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  • 4
    Electronic Resource
    Electronic Resource
    Study of the major fragmentation pathways of cypermethrin and related synthetic insecticides using tandem mass spectrometry (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 626-634 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fragmentation pathways of the synthetic pyrethroid cypermethrin and four structurally related insecticides were investigated using a tandem quadrupole mass spectrometer incorporating a hexapole collision cell under positive-ion electron impact ionization conditions. Conventional mass spectrometry using the first quadrupole analyser only and tandem mass spectrometry on selected precursor ions and product ions, and also constant neutral loss scan experiments, were used. Mechanisms and fragmentation pathways are proposed to explain the inherent stability of ions associated with the benzylphenoxy portion of this class of insecticide.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210280526
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  • 5
    Electronic Resource
    Electronic Resource
    The application of capillary electrophoresis/mass spectrometry using negative-ion electrospray ionization to areas of importance in the textile industry (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 179-182 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The feasibility of using capillary electrophoresis/mass Spectrometry, with negative-ion electrospray ionization, for applications of relevance to the dyeing and textile industries has been shown. Structurally similar examples of solubilized vat dyes of different halogen content have been separated and identified with a view to investigating the photodegradation processes which occur when the dyes are subjected to UV light. Separations of the various species formed when a mordant dye is chrome treated are also presented, indicating the ability to study complex formation arising from the different chrome dyeing methods.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080211
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  • 6
    Electronic Resource
    Electronic Resource
    Mass isotopomer analysis: Theoretical and practical considerations (1991)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 20 (1991), S. 451-458 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A theory of mass isotopomer analysis based on the well-known principle of isotope dilution mass spectrometry is reviewed. An algorithm for the determination of isotope incorporation into a metabolic substrate from a labeled precursor using mass isotopomer analysis is presented. The steps include the determination of the contribution of the derivatization reagent to the observed spectrum of the derivatized substrate and the correction of contribution from 13C natural abundance using multiple linear regression analysis. Examples of the application of this theory to determine the spectrum of the trimethylsilyl derivative of the ‘pure unlabeled’ or mononuclidic cholesterol, and the calculation of mass isotopomer distribution in cholesterol due to tracer incorporation using this ‘pure unlabeled’ spectrum, are also provided.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200200804
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  • 7
    Electronic Resource
    Electronic Resource
    Correction of glucose carbon recycling for the determination of ‘true’ hepatic glucose production rates by (1-13C1)glucose (1991)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 20 (1991), S. 186-190 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hepatic glucose production (HGP) and glucose carbon recycling are traditionally estimated by the combined use of hydrogen and carbon-labeled glucose tracers. A single-isotope method such as that of Reichard et al. for the determination of HGP and glucose carbon recycling requires the determination of activities in different glucose carbons by chemical degradation. Since the 13C content in the glucose carbon skeleton can be determined from mass fragmentography, the use of 13C-labeled glucose and mass fragmentography can provide a single-isotope method for the quantification of the recycled carbons. Correction for the recycling makes it possible to determine the true HGP.In this study, (1-13C1)glucose and mass fragmentography were used for the determination of HGP and glucose carbon recycling in six colon cancer patients. Molar enrichment of the molecular ion (m/z 328 cluster of glucose aldonitrile pentaacetate) was used to determine ‘unconnected’ HGP, which was 1.93 ± 0.11 mg kg-1 min-1 (mean ± s.e.m.). The difference in molar enrichment of the molecular ion C1-C6 (m/z 328) and the ion corresponding to C1-C4 fragment (m/z 242) was used to determine the contribution of recycled label carbon. After this correction, the ‘corrected’ HGP was 2.04 ± 0.12 mg kg-1 min-1, which is not significantly different from the ‘true’ HGP rate of 2.05 ± 0.15 mg kg-1 min-1 determined by using (6-3H)glucose. HGP determined from the enrichment of the molecular ion C1-C6 underestimates true HGP, as expected. The corrected HGPs correlate well with those from 6-3H method (r = 0.86, y = 1.06x - 0.12; p 〈 0.01). Calculated isotope carbon recycling determined as the difference between the uncorrected and the (6-3H)HGP is 4.5 ± 4.8% and is comparable to the 5.0 ± 3.3% determined by mass fragmentography. The use of (1-13C1)glucose tracer and measurement of recycling by mass fragmentography therefore provide a single-label, non-radioactive method for the determination of HGP rates.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200200405
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  • 8
    Electronic Resource
    Electronic Resource
    Analysis of Bacitracin B using fast atom bombardment and tandem mass spectrometry (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 22 (1993), S. 712-720 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bacitracin is a mixture of polypeptide antibiotics produced by the action of Bacillus subtilis and Bacillus licheniformis. The mixture has previously been shown to contain at least ten components, of which only the major component, Bacitracin A, and its oxidized counterpart, Bacitracin F, have been fully structurally evaluated. Using fast atom bombardment ionization with tandem mass spectrometry, three isobaric components of one of the minor constituents of the mixture, Bacitracin B, have been structurally characterized, delineating the three single substitution sites within Bactitracin A where Ile has been replaced by Val.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200221208
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  • 9
    Electronic Resource
    Electronic Resource
    Mass isotopomer pattern and precursor-product relationship (1992)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 21 (1992), S. 114-122 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a homonucleus polymer from its labeled precursor will lead to the formation of molecules with different masses. The distribution of these mass isotopomers is strictly a function of the enrichment of the 13C-labeled precursor, and can thus be used for the determination of the precursor enrichment and product dilution in the de novo synthesis of the polymer. We present here a study of the isotopomer pattern of a polymer of acetate in the form of glucose pentaacetate synthesized from 13C-enriched acetic anhydride. The molecular ion contains four acetyl units. Its synthesis is analogous to that of octanoic acid from acetyl coenzyme A. The process of obtaining the mass isotopomer distribution in the tetraacetyl moiety from the ion cluster of m/z 331 of glucose pentaacetate is illustrated. After correcting for the contribution of 13C natural abundance, the plot of the ratio of mass isotopomers (m4/m2) against the observed enrichment of the tetraacetate moiety yielded a straight line with a slope of 1.45. The ratio was not altered by dilution with pre-existing unenriched product, as predicted. The slope of the observed linear relationship agreed with the general formula (N - (j - 1))/j for the ratio of any two consecutive mass isotopomers (mj/mj-1). Theoretical and practical aspects of determining precursor enrichment from isotopomer pattern in polymers are discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200210210
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  • 10
    Electronic Resource
    Electronic Resource
    The preparation and characterization of new polyether ketone-tetraethylorthosilicate hybrid glasses by the sol-gel method (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 40 (1990), S. 1177-1194 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In recent years, tetraethyl orthosilicate (TEOS) has been used as a precursor in preparing inorganic glasses. The technique, known as the sol-gel process involves a two step poly(hydrolysis-condensation)reaction sequence. The work presented here is concerned with the utilization of a suitably functionalized oligomeric “glassy” organic polymeric component in this two step sequence. In particular, an amine terminated amorphous poly(arylene ether) ketone, (PEK), end capped with isocyantonropyl triethoxy silane was used to synthesize a hybrid network with TEOS. Low incorporation of the PEK oligomers into the network caused by early vitrification can be eliminated by carrying out reactions at elevated temperatures. A systematic change in mechanical and physical properties of the hybrid glass has been found with TEOS content and the annealing temperatures. A model for the network has been proposed based on structural and morphological evidence.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070400709
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