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  • Articles: DFG German National Licenses  (2)
  • 1980-1984  (2)
  • Gas co-distillation  (1)
  • pH-induced conformational change  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 261 (1983), S. 591-599 
    ISSN: 1435-1536
    Keywords: Copoly (N 5-ω-hydroxyalkyl-L-glutamine-L-glutamic acid) ; Solvent-induced conformational change ; pH-induced conformational change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Copoly (α-amino acid)s consisting ofL-glutamic acid residue andN 5-ω hydroxyalkyl-L-glutamine residue, i.e., 2-hydroxyethyl, 3-hydroxypropyl, and di-2-hydroxyethyl derivatives were prepared by the reactions of copoly (L-glutamic acid) containing succinimide ester with corresponding amino alcohols. The conformation of these copolymers was examined by the CD and infrared measurements. These three copolymers containing about 20–30% hydroxyalkyl groups undergo a methanol-induced and a pH-induced conformational transitions. The copolymer containing about 50% 3-hydroxypropyl group assumes the α-helical conformation in the pH region from 2.5 to 11.6, and in a methanol-water mixture (9∶1). On the other hand, the copolymer containing about 60% di-2-hydroxyethyl groups does not allow any helical conformation even at lower pH and also even in a trifluoroethanol-water mixture (9∶1), suggesting that the branched hydroxyalkyl group is unfavorable for the formation of α-helix. Furthermore, the poly(N 5-di-2-hydroxyethyl-L-glutamine) is shown to have a rather disordered structure in the solid state.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 15 (1982), S. 559-563 
    ISSN: 1612-1112
    Keywords: Gas co-distillation ; Tobacco essential oil ; Splitless injection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The essential oils have been isolated from tobacco leaves using a simple gas co-distillation apparatus. The method involves co-distillation with water under the continuous stream of an inert gas with subsequent single solvent extraction of the distillate. The extract is analysed on GC and GC/MS in splitless injection mode without further concentration. The method was evaluated for reproducibility using n-octadecane as an internal standard. The distillation-extraction procedure was reporducible with an average deviation of ±3% for the major constituents. The present method was applied to the analyses of the essential oils of other agricultural products.
    Type of Medium: Electronic Resource
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