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  • 1
    Electronic Resource
    Electronic Resource
    Photochromic polymers: effects of structure and environment on photoresponsiveness (1995)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 6 (1995), S. 32-41 
    Details
    ISSN: 1042-7147
    Keywords: Photochromism ; Polypeptides ; Acrylate polymers ; Photoresponsive macromolecules ; 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
    Notes: In this review paper the photoresponsiveness of photochromic macromolecules under different structural and environmental conditions is discussed with reference to results from the authors' laboratories. Polypeptides, in particular poly(L-glutamic acid) and poly(L-lysine), with spirobenzopyrane side chains show photoinduced conformational variations which are amplified by addition of organic acids or bases to hexafluoro-2-propanol (HFP) solutions. Thus combination of light and environment effects allows modulation of order-disorder conformational transitions.Such photoindiced conformational changes are not observed in the case of macromolecules with a hydrocarbon main chain and azobenzene or stilbene side chains, obtained by polymerization of acrylic monomers. However, even in these systems structural variations affect the dependence of optical properties on irradiation. Moreover, the combination of organic solvents and water shows that polymer solubility can be modulated by light.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1995.220060105
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  • 2
    Electronic Resource
    Electronic Resource
    Reaction of diazonium salt with tyrosine residues in polypeptides (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 3201-3209 
    Details
    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: Einige Copolymere aus L-Glutaminsäure und L-Tyrosin werden mit p-Carboxybenzoldiazoniumchlorid behandelt. Durch eine stöchiometrische Reagensmenge werden Monoazo-tyrosin-Chromophore in den Polypeptid-Ketten gebildet, während ein Reagensüberschuß zur Bildung einer Mischung von Mono- und Bisazoderivaten führt. In allen Fällen kann nur ein Teil der Tyrosin-Grundbausteine verändert werden. Die Ergebnisse werden mit den verschiedenen pKa-Werten für die Ionisierung der OH-Gruppen in den Tyrosin- und Azotyrosin-Grundbausteinen erklärt.
    Notes: Some copolymers of L-glutamic acid and L-tyrosine are treated with p-carboxybenzenediazonium chloride. Monoazotyrosine chromophores can be obtained along the polypeptide chains in the presence of a stoichiometric quantity of the reagent, whereas an excess of the reagent gives rise to the formation of a mixture of mono- and bis-azoderivatives. In all the cases only a part of the total number of the tyrosine residues can be modified. The results are discussed on the basis of the pKa values for the ionization of tyrosine and azo-tyrosine OH-groups.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021761106
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  • 3
    Electronic Resource
    Electronic Resource
    Liquid-crystalline structure of poly(L-lysine) containing azobenzene units in the side chain (1996)
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 17 (1996), S. 493-501 
    Details
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The structure of poly(L-lysine) containing 44% azobenzene units in the side chain was studied by X-ray diffraction between room temperature and 150°C. The polymer exhibits a mesomorphic structure of the smectic A1 type. In this structure, stable at least until 150°C, each smectic layer of thickness d results from the superposition of two layers: one of thickness dA contains the free lysine side chains, the other of thickness dB contains the azobenzene modified lysine side chains and the polypeptide main chains, that in their planes are arranged as in the “antiparallel” β-structure classical for polypeptides.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1996.030170801
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  • 4
    Electronic Resource
    Electronic Resource
    The photoresponse of an azobenzene-containing poly(L-lysine) in the monolayer state (1990)
    New York : Wiley-Blackwell
    Biopolymers 29 (1990), S. 1121-1123 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360290622
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  • 5
    Electronic Resource
    Electronic Resource
    Crystal and molecular structure of Boc-D-Ala-ΔPhe-Gly-ΔPhe-D-Ala-OMe: A 310-helical dehydropeptide (1990)
    New York : Wiley-Blackwell
    Biopolymers 30 (1990), S. 911-920 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal and molecular structure of the pentapeptide Boc-D-Ala-ΔPhe-Gly-ΔPhe-D-Ala-OMe, containing two dehydrophenylalanine residues, was determined by x-ray diffraction. The molecule crystallizes in the orthorombic P212121 space group, with a = 10.439(3), b = 15.319(3) and c = 21.099(4) Å.In the solid state, the conformation of the pentapeptide is characterized by the presence of two type III′ β-turns. Thus the peptide assumes a left-handed 310-helical conformation, the left sense being due to the D configuration of the alanine residues. The two unsaturated residues are located in the (i + 1) position of the first β-turn and in the (i + 2) position of the second β-turn, respectively.In the crystal, the helical molecules are linked head to tail by hydrogen bonds. Lateral hydrogen bonds are also formed between molecules related by a twofold screw symmetry. This gives rise to a typical mode of packing characterized by infinite helical “chains,” smiliar to the packing found in other oligopeptides that adopt a 310-helical structure.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360300906
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  • 6
    Electronic Resource
    Electronic Resource
    Chiroptical properties of unsaturated peptides (1973)
    New York : Wiley-Blackwell
    Biopolymers 12 (1973), S. 1445-1449 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1973.360120619
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  • 7
    Electronic Resource
    Electronic Resource
    Optical acitivity and photochromism of the azo chromophore bound to poly(L-glutamic acid) (1978)
    New York : Wiley-Blackwell
    Biopolymers 17 (1978), S. 799-804 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1978.360170319
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  • 8
    Electronic Resource
    Electronic Resource
    Crystal and molecular structure of the doubly unsaturated dehydropeptide Ac-ΔPhe-Ala-ΔPhe-NH-Me (1992)
    New York : Wiley-Blackwell
    Biopolymers 32 (1992), S. 717-724 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dehydropeptide Ac-ΔPhe-L-Ala-ΔPhe-NH-Me, containing two dehydro-phenylalanine (ΔPhe) residues, crystallizes from methanol/water in space group P212121, with a = 12.508 (2), b = 12.746(1) and c = 15.465(9).In the crystalline state, the peptide chain assumes a right-handed 310-helical conformation stabilized by two intramolecular hydrogen bonds, between the N-terminal acetyl group and the NH of ΔPhe3, and between the CO of ΔPhe1 and the NH of the C-terminal methylamide group, respectively. The two consecutive 10-membered rings formed by the hydrogen bonds have torsion angles quite close to the standard values for type III β-bends. ΔPhe1 is located in the (i + 1) position of the first β-bend, while ΔPhe2 is located in the (i + 2) position of the other β-bend.In the crystal, the molecules are linked head to tail by intermolecular hydrogen bonds to form long helical chains. The axes of the helices are parallel to the c axis, but neighboring helices run in antiparallel directions. This crystal packing is similar to the packing motifs frequently observed in Aib-containing peptides.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360320702
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  • 9
    Electronic Resource
    Electronic Resource
    Solution structure of peptides containing two dehydro-phenylalanine residues: A CD investigation (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 1-10 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The peptides Ac-ΔPhe-Ala-ΔPhe-NH—Me (1), Ac-ΔPhe-Val-ΔPhe-NH—Me (2), Ac-ΔPhe-Gly-ΔPhe-Ala-OMe (3), and Boc-Ala-ΔtPhe-Gly-ΔPhe-Ala-OMe (4), containing two dehydro-phenylalanine (ΔPhe) residues, were synthesized and the solution structure investigated in various solvents. The nmr and CD measurements indicate that all the dehydropeptides examined adopt 310-helical conformations in solution. The tripeptides 1 and 2 exibited an intense negative CD exciton couplet, which was assigned to the right-handed screw sense, while the tetrapeptide 3 displayed a CD couplet having opposite sign, which was assigned to the left-handed helical sense. In the pentapeptide 4 the sense of the helix was found to vary with solvent and temperature, as demonstrated by the sign reversal of the CD spectrum. The right-handed sense dominates in hexafluoro-2-propanol, whereas a left-handed helix prevails in chloroform, acetonitrile and methanol. A crucial role for this behavior is likely to be played by the two alanine residues positioned respectively at the head and tail of the sequence, which favor conformations having opposite screw senses. © 1993 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360330102
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  • 10
    Electronic Resource
    Electronic Resource
    Unsaturated amino-acid residues as probes for the conformation of polypeptides in solution (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1677-1686 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acetyl-(dehydro-Phe) and acetyl-bis(dehydro-Phe) groups have been attached to the ε-amino group of the lysine residues of the copolymer poly(Glu92Lys8) by reacting this last with acetyl-(dehydro-Phe)-azlactone and acetyl-bis(dehydro-Phe)-azlactone, respectively.In the latter case induced CD is observed between 250 and 330 nm, due to the relative dissymmetric disposition of the two dehydro-Phe groups under the chiral field of the polypeptide chain.pH dependence of the induced CD, observed for the copolymer and lacking in the lowmolecular-weight structural model, is related to the α-helical and random coiled conformation of the polypeptide chain.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160806
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