ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The conformational properties of two series of monodispersed, chemically and optically pure, PEGThe following abbreviations have been used in the text: PEG, poly(ethylene glycol); -NHPEG, “amino-PEG”; -NHPEG-M, “amino-PEG” monomethyl ether; NPS, o-nitrophenylsulfenyl; t-Boc, tert-butoxycarbonyl; Z, benzyloxycarbonyl; Met, methionine; Pro, proline; OBzl, benzyloxy; OMe, methoxy; OEt, ethoxy; NHEt, ethylamino; Glu, glutamic acid; IR, infrared; MeOH, methanol; TFE, 2,2,2-trifluoroethanol.-bound linear host oligopeptides of the general formula \documentclass{article}\pagestyle{empty}\begin{document}$ t{\rm - Boc\rlap{--} (L - Met\rlap{--} )}_n {\rm NHPEG} $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ t{\rm - Boc\rlap{--} [L - Glu(OBl)\rlap{--} ]}_n {\rm NHPEG - M} $\end{document} containing a single guest L-Pro residue at different positions in the main chain have been investigated in the solid state using IR absorption. The corresponding N-deblocked peptides have also been examined. The incorporation of a L-Pro residue in a central position of a β-conformation appears to induce the onset of a structural irregularity characterized by IR absorption bands in the vicinity of 3 325 cm-1 and 1 575 cm-1.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The conformational properties of three series of monodispersed, chemically and optically pure, PEGThe following abbreviations have been used in the text: PEG, poly(ethylene glycol); -NHPEG, “amino-PEG”; -NHPEG-M, “amino-PEG” -monomethyl ether; t-Boc, tert-butyloxycarbonyl; Z, benzyloxycarbonyl; Ala, alanine; Met, methionine; Gly, glycine; Glu, glutamic acid; Pro, proline; OBzl, benzyloxy; OEt, ethoxy; CD, circular dichroism; MeOH, methanol; TFE, 2,2,2-trifluoroethanol; HFIP, 1,1,1,3,3,3-hexafluoro-2-propanol.-bound linear host oligopeptides of the general formula \documentclass{article}\pagestyle{empty}\begin{document}$ t{\rm - Boc\rlap{--} (L - Met\rlap{--} )}_n {\rm NHPEG} $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ t{\rm - Boc\rlap{--} (L - X\rlap{--} )}_n {\rm NHPEG - M} $\end{document} [X = Ala, Glu(OBzl)] containing a single guest L-Pro residue at different positions in the main chain have been investigated in aqueous and alcoholic solutions as a function of concentration, temperature, and added salts using CD. The corresponding N-deblocked peptides have also been examined. The incorporation of the L-Pro residue into a host petide chain blocks the extension of the α-helical conformation at the level of the segment containing the guest residue at its N-terminal end. The investigations reveal asymmetric helixnucleation properties of the L-Pro residue as predicted by theory. In β-structure-forming oligopeptides, the insertion of a L-Pro residue results in a significant destabilization of the ordered conformation. Thus, aggregation of peptide chains is less pronounced in these co-oligopeptides.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Konformation einer Reihe von molekulareinheitlichen, chemisch und optisch reinen geschützten L-Alanin-Homo-Oligomeren mit der allgemeinen Formel BOC—(L-Ala)n—OCH3 (n=2-7) wurden in Lösung mit Hilfe der CD-Methode untersucht. Es wurde gefunden, daß diese Peptide in einem hauptsächlich β-assoziierten statistischen Knäuel oder in partiell α-helicalen Konformationen auftreten können, abhängig vom Molekulargewicht, Lösungsmittel, Temperatur und Oligomerenkonzentration. Die β-Struktur, die im Bereich 5≤n≤7 in 2,2,2-Trifluoräthanol (TFE), TFE-Wasser 20:80 (V/V), Methanol und Äthanol auftrat, konnte durch Verdünnung oder Temperaturerhöhung zerstört werden. In verdünnter TFE-Lösung wurde die Tendenz des Heptameren zur Kettenfaltung gefunden. In 1,1,1,3,3,3-Hexafluorpropan-2-ol und Hexafluoraceton-ses-quihydrat treten alle Oligomeren jedoch ausschließlich in einer ungeordneten Konformation auf.
    Notes: The conformational properties in solution of a series of monodisperse, chemically and optically pure protected L-alanine homo-oligomers, having the general formula BOC—(L-Ala)n—OCH3 (n = 2-7), were investigated using essentially the CD technique. This study demonstrates that these peptides may exist in predominantly β-associated, statistical coil, or partially α-helical conformations depending upon molecular weight, solvent, temperature, and oligomer concentration. The β-structure, which appears in the range 5≤n≤7 in 2,2,2-trifluoroethanol (TFE), TFE-water 20:80 (v/v), methanol, and ethanol could be destroyed by dilution or by increasing the temperature. In diluted TFE solutions, the tendency of the heptamer to form folded species could be detected. In 1,1,1,3,3,3-hexafluoropropan-2-ol and hexafluoroacetone sesquihydrate, however, all oligomers exist essentially in an unordered conformation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Eine Reihe von geschützten L-Alanin-Homo-Oligomeren vom Dimeren bis zum Heptameren wurde durch die Dicyclohexylcarbodiimid- und Azidkupplung dargestellt. Als N-Schutzgruppe wurde der tert-Butoxycarbonylrest und als C-Schutzgruppe die Methylestergruppe verwendet. Die so synthetisierten molekulareinheitlichen Oligomeren wurden charakterisiert und erwiesen sich als chemisch rein. Die polarimetrische Untersuchung in einem denaturierenden Lösungsmittel zeigte, daß alle Reaktionen unter vollständiger Erhaltung der Konfiguration erfolgten. Außerdem wurde die Abhängigkeit der experimentell gefundenen Werte der Molekularrotation der innenständigen L-Alaninreste bei 589 nm im statistischen Knäuel von der Struktur der Endgruppen und dem Lösungsmittel besonders herausgestellt.
    Notes: A series of protected L-alanine homo-oligomers from dimer to heptamer was prepared by the dicyclohexylcarbodiimide and acyl azide coupling methods. In the course of the synthetic approach tert-butoxycarbonyl as the N-protecting and methyl ester as the C-protecting end groups were employed. The monodisperse oligomers prepared in this manner were characterized and found to be chemically pure. A polarimetric investigation in a structure disrupting solvent also indicated that all reactions proceeded with complete retention of the configuration. In addition, the dependence of the experimental molar rotation values at 589 nm of L-alanine internal residues in a polypeptide in a statistical coil conformation on the end groups of the molecule and the solvent is emphasized.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die IR-Spektren von 8 Reihen von molekulareinheitlichen, chemisch und optisch reinen, geschützten linearen Homo-Oligopeptiden mit der allgemeinen Formel Boc(—L—X)n—OMe (mit X = Ala, Nva, Val, Leu, Ile, Phe, Met, Cys(Me) und n = 2-7) wurden durch IR-Absorptionsspektroskopie im festen Zustand und in Lösung untersucht. Die Messungen im festen Zustand ergaben, daß alle Pentameren und höheren Oligomeren hauptsächlich eine β-Form einnehmen. Trimere und Tetramere bestehen danach aus Mischungen von β- und ungeordneten Strukturen, während in den Dimeren die ungeordnete Struktur vorherrscht. Das Auftreten der ungewöhnlichen intermolekularen parallelen βKonformation wird für HCl·H(—L—X)7—OMe (mit X = Val, Ile, Phe) vorgeschlagen. Außerdem wurde die Absorption im Gebiet der N—H-Valenzschwingung in Abhängigkeit von der Konzentration in Deuterochloroform bestimmt. Diese Konformationsanalyse in Lösung zeigte, daß ein hoher Gehah an Strukturen mit intramolekularen Wasserstoffbrücken in allen Homo-Tetrameren vorliegt, mit Ausnahme der Derivate mit β-verzweigten Aminosäureresten (Valin, Isoleucin). Der Effekt eines Schwefelatoms und eines aromatischen Rings in der Seitenkette (S-Methplcystein - Methionin - und Phenylalanin-Peptide) auf die Stabilitlt der gefalteten Formen wird ebenfalls diskutiert.
    Notes: The IR spectra of eight series of monodisperse, chemically and optically pure, protected linear homo-oligopeptides having the general formula Boc(—L—X)n—OMe, where X = Ala, Nva, Val, Leu, Ile, Phe, Met, Cys(Me), and n = 2-7, were investigated by IR absorption spectroscopy in the solid state and in solution. The measurement in the solid state indicate that all pentamers and higher oligomers assume essentially a β-form; trimers and tetramers present evidence of mixtures of β- and unordered structures, while in dimers the unordered structure is largely predominant. The occurrence of the unusual intermolecular β-parallel conformation was suggested for HCl·H(—L—X)7—OMe, where X = Val, Ile, and Phe. Further, the absorbance in the N—H stretching region was determined as a function of concentration in deuterochloroform. This conformational analysis in solution showed that a high content of intramolecularly hydrogen-bonded forms exist in all homo-tetramers with the exception of those derived from the β-branched amino acid residues, valine and isoleucine. The effect of the presence of a sulfur atom or an aromatic ring in the amino acid side chain (S-methyl cysteine, methionine, and phenylalanine peptides) on the stability of the folded forms is also discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The IR absorption properties of three series of monodisperse, chemically and optically pure, PEG-bound linear homo-oligopeptides having the general formula t-Boc-(L-Ala-)1-8Gly-OPEG, t-Boc-(L-Val-)1-7Gly-OPEG and t-Boc-(L-Val-)2-8Gly-OPEG-M were investigated in the solid state and in solution. In the latter case the study was extended to solvents of largely different polarity and different concentrations. In the solid state the Ala and Val peptides from n = 5 to n = 8 assume essentially a β-structure. The occurrence of the unusual parallel-chain β-conformation was suggested for the N-deblocked Val highest peptides. The conformational analysis in deuterochloroform at high dilution showed that a much higher content of intramolecularly H-bonded forms exist in Ala4 than in the Val4 peptides. At higher concentrations chain length, solvent, and side chain effects are all operative in determining the extent of peptide association. The influence of the bi- and monofunctional polymeric supports on the conformational properties of the Ala and Val homo-oligopeptide series is also discussed. Finally, preliminary results on the relationship between reactivity of the polymer-bound growing peptide chain during the step-by-step synthesis and peptide conformation are reported.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...