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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Endothermic reactions between leucine enkephalin and ammonia have been carried out at very low beam energies, and compared with activation obtained by conventional collision-induced dissociation at both low and high energies. The similarity between the high-energy and the reactive-collisions spectra suggest that comparable energies are imparted by these two methods. The upper limit of the collision energy deposited by reactive collisions is only 0.30 eV. In addition, a substantial increase in the collection efficiency is observed with endothermic reactions, with the sum of the fragment ions exceeding the intensity of the surviving parent ions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The design and Performance of a short-pulse UV laser desorption time-of-flight mass spectrometer is described. The instrument combines the advantages of a 600 ps, 337 nm Pulsed nitrogen laser with a compact, high-voltage extraction linear time-of-flight analyzer. A number of peptides and proteins have been analyzed to demonstrate senstivity, high mass range, resolution and mixture analysis.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A new type of curved-field reflectron has been developed for the energy focusing of ions formed after initial acceleration in time-of-flight (TOF) mass spectrometers. These include ions generated in the dissociation region of a tandem TOF, as well as metastable decay products formed in the field-free drift region prior to their reflection. Unlike conventional linear-field reflectrons, which focus product ions to different focal lengths that are proportional to the mass (energy) of the fragment, the new curved-field reflectron energy focuses all ions to within a small region near the exit of the reflectron. Thus, the collection of resolved fragment peaks is possible without scanning or stepping the potential gradient of the reflectron, enabling faster acquisition of the production spectrum and, more importantly, true multiplex recording of the spectra from each ionization event. Theoretical considerations of the design are discussed along with an evaluation of collision-induced dissociation data, demonstrating the performance of the new reflectron in a tandem TOF instrument.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Mass spectra of several model oligopeptides (substance P, [Arg8]-vasopressin, tyrothricin, and the B-chain of bovine insulin) have been obtained with a matrix-assisted laser desorption/ionization (MALDI) source and a custom-designed Fourier-transform mass spectrometer (FTMS). The MALDI source is outside the magnetic field in a separately pumped external chamber, and ions are injected through the fringing fields of the magnet and into the FTMS analyzer cell by a long quadrupole mass filter that is operated in the RF-only mode. A large window on the ion source housing makes it easy to point and focus the laser beam onto the sample probe tip. A good quality mass spectum is achieved for 0.5 pmol of substance P, and the mass resolution for the B-chain of bovine insulin is 19000.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1986), S. 395-400 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For molecules over 5000u, abundances of multiply-charged molecular ions in the fast atom bombardment mass spectra reflect changes in the pH of the sample. This result follows from the production of stable multiply-charged ions with desorption rates comparable to that of singly-charged ions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0887-3585
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: No abstract.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 591-598 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Laser desorption mass spectrometry has been employed for the structural determination of lipid A components derived from the lipopolysaccharides (LPS) of gram-negative bacteria. Mass spectra were obtained for methylated monophosphoryl lipid A from Neisseria gonorrhoeae and Rhodopseudomonas sphaeroides, for diphosphoryl lipid A from Escherichia coli and for the intact LPS from the Re Mutant of E. coli consisting of triphosphoryl lipid A and two KDO (2-keto-3-deoxyoctonate) units. Fragmentation of the phosphate (or pyrophosphate) on the reducing glucosamine is followed by fragmentation of acyl-linked fatty acids. Also observed are fragmentions which correspond to the distal portion of the molecule.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0887-3585
    Keywords: ion/molecule reactions ; hydrogen/deuterium exchange ; ion trap ; MALDI ; peptide ions ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Hydrogen/deuterium exchange reactions of protonated and sodium cationized peptide molecules have been studied in the gas phase with a MALDI/quadrupole ion trap mass spectrometer. Unit-mass selected precursor ions were allowed to react with deuterated ammonia introduced into the trap cell by a pulsed valve. The reactant gas pressure, reaction time, and degree of the internal excitation of reactant ions were varied to explore the kinetics of the gas phase isotope exchange. Protonated peptide molecules exhibited a high degree of reactivity, some showing complete exchange of all labile hydrogen atoms. On the contrary, peptide molecules cationized with sodium exhibited only very limited reactivity, indicating a vast difference between the gas phase structures of the two ions. © 1997 Wiley-Liss Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0887-3585
    Keywords: non-covalent interaction ; DNA ; peptides ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: DNA-histone interaction facilitates packaging of huge amounts of DNA in the confined space of the nucleus. The importance of this interaction underscores the need for new analytical techniques to acquire a better understanding of nuclear dynamics. Electrospray-ionization mass spectrometry made it possible to investigate non-covalently-bound biopolymers. We are enlarging the scope of available analytical tools by studying non-covalent interaction between single and double stranded DNA and peptides with matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The interaction is an ionic one, between the negatively charged sugar-phosphate backbone of single stranded DNA and positively charged side chains of Arg- and Lys-rich peptides as demonstrated by Vertes' group1 with the dipeptides Arg-Lys and His-His. We replicated Lecchi and Pannell's work,2 which showed that double stranded DNA could be seen by MALDI using 6-aza-2-thiothymine (ATT) as matrix. We tried various peptides and found that as was demonstrated in DNA-histone interaction, a certain ratio and arrangement of basic residues was needed in order to generate ionic binding between DNA and peptide. We tested various single and double stranded DNA with the peptide of choice, and found that other variables such as pH value of solution, ionic strength, and matrix system did play a role. Proteins Suppl. 2:12-21, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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