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  • 1
    ISSN: 1573-4951
    Keywords: α-helical model system ; Conformational analysis ; Counterpoise method ; Hartree-Fock calculations ; Histamine H2 receptor ; Molecular mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Mutation studies on the histamine H2 receptor were reported by Gantz et al. [J. Biol. Chem., 267 (1992) 20840], which indicate that both the mutation of the fifth transmembrane Asp186 (to Ala186) alone or in combination with Thr190 (to Ala190) maintained, albeit partially, the cAMP response to histamine. Recently, we have shown that histamine binds to the histamine H2 receptor as a monocation in its proximal tautomeric form, and, moreover, we suggested that a proton is donated from the receptor towards the tele-position of the agonist, thereby triggering the biological effect [Nederkoorn et al., J. Mol. Graph., 12 (1994) 242; Eriks et al., Mol. Pharmacol., 44 (1993) 886]. These findings result in a close resemblance with the catalytic triad (consisting of Ser, His and Asp) found in serine proteases. Thr190 resembles a triad's serine residue closely, and could also act as a proton donor. However, the mutation of Thr190 to Ala190 — the latter is unable to function as a proton donor — does not completely abolish the agonistic cAMP response. At the fifth transmembrane α-helix of the histamine H2 receptor near the extracellular surface, another amino acid is present, i.e. Tyr182, so an alternative couple of amino acids, Tyr182 and Asp186, could constitute the histamine binding site at the fifth α-helix instead of the (mutated) couple Asp186 and Thr190. In the first part of our present study, this hypothesis is investigated with the aid of an oligopeptide with an α-helical backbone, which represents a part of the fifth transmembrane helix. Both molecular mechanics and ab initio data lead to the conclusion that the Tyr182/Asp186 couple is most likely to act as the binding site for the imidazole ring present in histamine.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 29 (1998), S. 609-617 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Microstructural, mechanical and corrosive properties of friction stir welded aluminium jointsFriction stir welding (FSW) is a novel solid state welding process. It allows joining of high strength aluminum alloys, generally considered as difficult-to-weld with conventional technologies, without loss in joint strength. Results of investigations on selfmade FSW butt joints of the aluminum alloys 2024-T3 and 6013-T4 are presented. First, the microstructure of the weld seam and heat affected zone is characterised metallographically and by hardness measurements. By tensile, fatigue endurance (SN) and fatigue crack propagation tests it is demonstrated, that especially the FSW-joints of 2024-T3 sustain high mechanical loadings. Investigations on the corrosion properties reveal a certain sensitivity of the 2024-T3 joints to intergranular and exfoliation corrosion.
    Notes: Das Reibrührschweißen (friction stir welding FSW) ist ein neues Fügeverfahren, mit dem auch die schwer schmelzschweißbaren, höherfesten Aluminiumlegierungen ohne große Festigkeitsverluste verschweißt werden können. Erste Ergebnisse von Untersuchungen an selbst hergestellten FSW-Stumpfnähten der Aluminiumlegierungen 2024-T3 und 6013-T4 werden vorgestellt. Zunächst wird das Gefüge der Naht und der Wärmeeinflußzone mikrostrukturell und durch Härteverläufe charakterisiert. Weiterhin wird mit Zug-, Schwingfestigkeits- und Rißfortschrittsversuchen nachgewiesen, daß insbesondere die FSW-Nähte der Legierung 2024-T3 außerordentlich hohe mechanische Belastungen ertragen. Abschließende Korrosionsuntersuchungen der FSW-Nähte zeigen eine gewisse Anfälligkeit der abschreckempfindlichen Legierung 2024-T3 für interkristalline Korrosion und Schichtkorrosion.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 71-74 
    ISSN: 0935-6304
    Keywords: On-line coupled LC-GC ; Loop-type interface ; Mixing in the sample loop ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: During introduction of an LC fraction into the sample loop of the loop-type interface mixing occurs between the fraction of interest and the material previously eluted from the LC. Such mixing may not only result in losses of the solute material of interest, but also in contamination of the fraction of interest with material from which it was supposed to have been isolated. Experimental determination of the extent of mixing has led to the conclusion that whereas the effects are negligible under some conditions, in some circumstances the mixing can cause severe problems.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 17 (1836), S. 191-192 
    ISSN: 0365-5490
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 20 (1836), S. 71-73 
    ISSN: 0365-5490
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Unknown
    Grand Rapids, Mich : Christian Classics Ethereal Library
    Keywords: Death, Sermons. ; Sermons, English.
    ISBN: 0-585-03584-9
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  • 7
    Unknown
    Grand Rapids, Mich : Christian Classics Ethereal Library
    Keywords: Church of England, Sermons. ; Sermons, English.
    ISBN: 0-585-07463-1
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