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  • Chemistry  (56)
  • 1980-1984  (23)
  • 1975-1979  (25)
  • 1960-1964  (5)
  • 1950-1954
  • 1935-1939  (3)
  • 1920-1924
  • 1
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A strategy suitable for the synthesis of larger peptides is proposed. It involves the following four considerations: (1) all of the side-chain functional groups are protected by benzyl-type protective groups; (2) a water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide, is used for the fragment-condensation reactions together with 1-hydroxybenzotriazole as the additive; (3) all the protective groups are cleaved simultaneously by the HF method in the final stage of the synthesis; and (4) side products formed are detected and removed by an efficient high-performance liquid chromatography procedure. The usefulness of these procedures is demonstrated taking the synthesis of human parathyroid hormone [hPTH(1-84)] as an example.
    Additional Material: 8 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 2191-2206 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclic octapeptides, cyclo(X-Pro)4, where X represents Phe, Leu, or Lys(Z), were synthesized and their conformations investigated. A C2-symmetric conformer containing two cis peptide bonds was found in all of these cyclic octapeptides. The numbers of available conformations due to the cis-trans isomerization of Pro peptide bonds depended on the nature of the solvent and X residue: they decreased in the following order: cyclo[Lys(Z)-Pro]4 〉 cyclo(Leu-Pro)4 〉 cyclo(Phe-Pro)4 in CDCl3. 13C spin-lattice relaxation times (T1) of these cyclic octapeptides were measured, and the contribution of segmental mobility to T1 was found to vary with the nature of the X residue.
    Additional Material: 12 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 23-38 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general method is presented for computing the atomic coordinates of helices in which a dipeptide is the repeating unit. The method will generate both single- and double-stranded model helices having idealized bond lengths and angles, and any arbitrary, user-specified, pitch and number of residues per turn. The variation of inter- and intrastrand hydrogen bonds with pitch and number of residues per turn can thus be examined. An application of the method is the construction of a β-helix having pitch of 6.3 Å per turn and 4.85 residues per turn, a model which can pack nicely into the unit cell of crystals of cation-bound gramicidin A.
    Additional Material: 9 Ill.
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  • 4
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A cyclic pentapeptide containing an energy donor group and an energy acceptor group within the molecule, cyclo [Trp-Sar-Sar-Lys (DNS)-Pro], was synthesized. Its conformation, complexation with metal ions, intramolecular energy transfer, and interaction with liposomes were investigated. The precursor, cyclo [Trp-Sar-Sar Lys (Z)-Pro], contained one cis-sarcosyl peptide bond and a β-turn in which the Pro-residue occupied the 3rd position. This cyclic pentapeptide formed a complex selectively with Ba2+ and its binding constant in 95% aqueous methanol solution was 2.0 × 103 1 · mol-1. The intramolecular energy-transfer efficiency of cyclo [Trp-Sar-Sar-Lys (DNS)-Pro] was almost constant between - 60° and 40° in ethanol, while it increased at temperatures lower than 34° in liposomes as a result of the pre-transition of the lipid assembly. On the other hand, the intramolecular energy transfer efficiency of cyclo [Trp-Sar-Sar-Lys (DNS)-Pro] decreased upon complexation with Ba2+.
    Additional Material: 8 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 177 (1976), S. 1235-1241 
    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: Benzyl-2-(methacryloyloxy)äthyl-2′-(phthalimido)äthylphosphat (1) und 2-(Methacryloyloxy)äthyl-2′-(phthalimido)äthyl-hydrogenphosphat (3) wurden dargestellt, charakterisiert und mit 2,2′-Azoisobutyronitril polymerisiert. Die Eigenschaften der erhaltenen Polymere werden beschrieben.
    Notes: Benzyl 2-(methacryloyloxy)ethyl 2′-(phthalimido)ethyl phosphate (1) and 2-(methacryloyloxy)ethyl 2′-(phthalimido)ethyl hydrogen phosphate (3) were synthesized, characterized, and polymerized with 2,2′-azoisobutyronitrile. The properties of the resultant polymers are described.
    Additional Material: 3 Ill.
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  • 6
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The hydrophobic surface of oriented poly(propylene) film (OPP) was modified to a hydrophilic one by a novel photo-grafting procedure using acrylamide (AM) as monomer. A deoxygenated acetone solution containing AM and benzophenone (BP) or other sensitizers was brought into contact with OPP film and the reaction system was photoirradiated from the other side of the polymer film. Within a few minutes, surface photo-grafting resulted. The influences of solvent, sensitizer, and additives revealed that the graft polymerization was initiated by hydrogen abstraction from the polymer surface by the triplet excited state of the sensitizer. IR Spectroscopy as well as ESCA measurements confirmed that the graft polymerization occurred on the film surface. The wettability of the grafted OPP film is discussed and correlated with the relative amount of surface grafting. The contact angle of untreated OPP film to water (101°) decreased to ≈40° after surface photografting. The drastic change of surface properties makes the practical application of the present technique feasible.
    Additional Material: 8 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 2225-2239 
    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 Chelatbildung der Vinylamin/Vinylalkohol-Copolymeren mit Kupfer(II)ionen wurde sowohl spektrophotometrisch als auch titrimetrisch untersucht. Zum Vergleich wurden weiterhin Gemische aus Polyvinylamin und Polyvinylalkohol vermessen. Es ergab sich, daß die Kupfer(II)ionen im Falle der Copolymersysteme ausschließlich von den Stickstoffatomen des Copolymerliganden koordiniert werden. Die Komplexierungskonstanten der Chelate wurden durch Anwendung der modifizierten Bjerrumschen Methode - unter Vernachlässigung der Säuredissoziation der Copolymer-Hydroxygruppen - bestimmt. Es ergab sich. daß die Copolymer/Kupfer(II)chelate mit abnehmendem Gehalt an NH2-Gruppen in den Copolymeren instabiler werden. Im Falle der Homopolymer-Gemische werden die Kupfer(II)ionen nur von den Stickstoffatomen des Polyvinylamins, nicht aber von den Sauerstoffatomen des Polyvinylalkohols koordiniert.
    Notes: Chelate formation of vinylamine/vinyl alcohol copolymers with copper(II) was studied both by the spectrophotometric and by titrimetric methods. For comparison, polyvinylamine/poly(vinyl alcohol) mixtures were also taken up for measurements. In the case of the copolymer systems, copper(II) ions were found to be coordinated exclusively by nitrogen atoms of the copolymer ligand. The complexation constants of the chelates were determined by applying the modified Bjerrum method, in neglect of the acid dissociation of hydroxy groups in the copolymers. It was found that the copolymer/Cu(II) chelates tend to be unstable with decreasing contents of NH2 groups in the copolymers. In the homopolymer mixture systems, copper(II) ions are not coordinated by the oxygen atoms of poly(vinyl alcohol), but only by the nitrogen atoms of polyvinylamine.
    Additional Material: 11 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 3425-3431 
    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: Verdünnungsenthalpien für Poly(1-vinyl-2-pyrrolidon), (Poly[1-(2-oxopyrrolidin-1-yl)-ethylene]), in wäßrigen Methanollösungen von unterschiedlichem Methanolgehalt, wurden bei 298 K gemessen. Das Molekulargewicht des Polymeren betrug 10000 bzw. 40000.Die experimentellen Ergebnisse wurden nach einer modifizierten Tompa-Gleichung mit konzentrationsabhängigem Wechselwirkungsparameter analysiert und so der Wechselwirkungsparameter zwischen dem Polymeren und dem Mischlösungsmittel für unendliche Verdünnung erhalten.Der Einfluß von Methanol auf die Wechselwirkung zwischen dem Polymeren und Wasser wurde aufgrund der Änderungen des Wechselwirkungsparameters bei unendlicher Verdünnung für die Überführung des Polymeren von Wasser in wäßriges Methanol diskutiert.
    Notes: Enthalpies of dilution of poly(1-vinyl-2-pyrrolidone), (poly[1-(2-oxopyrrolidin-1-yl)ethylene]), in aqueous methanol solutions of different methanol contents were measured at 298 K. The molecular weight of the polymer was 10000 and 40000, respectively.The experimental results were analysed with a modified Tompa formula containing an interaction parameter dependent on concentration; so the interaction parameter at infinite dilution between the polymer and the mixed solvent was derived.The influence of methanol on the interaction between polymer and water molecules was discussed from the change of the interaction parameter at infinite dilution for the transfer process from water to aqueous methanol solvent.
    Additional Material: 3 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 177 (1976), S. 1973-1979 
    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: Es werden die Darstellungen von Benzyl-2-(p-methacryloyloxybenzoyl)äthyl-2′-(phthalimido)äthyl-phosphat (3) und 2-(p-Methacryloyloxybenzoyl)äthyl-2′-(phthalimido)äthyl-hydrogen-phosphat (6) beschrieben. Die Monomeren werden charakterisiert und mit 2,2′-Azoisobutyronitril (AIBN) polymerisiert. Die Eigenschaften der erhaltenen Polymeren werden beschrieben.
    Notes: Benzyl 2-(p-methacryloyloxybenzoyl)ethyl 2′-(phthalimido)ethyl phosphate (3) and 2-(p-methacryloyloxybenzoyl)ethyl 2′-(phthalimido)ethyl hydrogen phosphate (6) were prepared, characterized, and polymerized with 2,2′-azoisobutyronitrile (AIBN). The properties of the resultant polymers are described.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 185 (1984), S. 749-755 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The blue colored complex between poly(vinyl alcohol) (PVA) and iodine was prepared at 5°C by mixing an aqueous solution of PVA with an aqueous ethanolic solution of iodine containing boric acid. The absorption spectrum of the system shows bands at 226 nm (A), 290 nm (B), 355 nm (C), and 650 nm (D). Their relative absorbances change largely depending on temperature. When the system is gradually warmed, the chromophoric band D decays and the intensity of band A increases. By lowering the temperature again to 5°C the concentration of chromophore increases. It was found that the decay and the re-formation of the chromophore are reversible in the temperature range 5 to 15°C. Above 15°C, contrarily, hysteresis effects are encountered for the re-formation. Thus, when the chromophore is re-formed at 5°C, the spectra shows an isosbestic point at 420 nm, between bands C and D. The dependence on temperature of bands B and C is quite independent from each other, which strongly indicates that the latter band should be assigned to another iodide species than the I-3 ion (band B) and the I- ion (band A). Based on these experimental data a new mechanism is proposed involving the complex ion I-3 · I2 which is supposed to be a precursor of the chromophoric pentaiodide ion I5-.
    Additional Material: 3 Ill.
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