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  • Chemistry  (36)
  • 2020-2024
  • 2005-2009
  • 1995-1999  (13)
  • 1990-1994  (20)
  • 1980-1984  (3)
  • 1965-1969
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  • 1
    Electronic Resource
    Electronic Resource
    Solution structure of human growth hormone-releasing factor fragment (1-29) by CD: Characteristic conformational change on phospholipid membrane (1991)
    New York : Wiley-Blackwell
    Biopolymers 31 (1991), S. 869-876 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformations of synthetic human growth hormone-releasing factor fragment (1-29) in the presence and the absence of l, 2-dimyristoyl-sn-glycero-3-phosphorylglycerol liposome as well as in aqueous 2, 2, 2-trifluoroethanol solution were investigated by CD spectroscopy. The secondary structure of the peptide in each solution was analyzed by two methods. Both results show that the peptide has an unordered structure in the aqueous solution. whereas it folds into helical structure in the aqueous alcohol and in the phospholipid solution. In addition, although the peptide exists as almost complete helix in the 50 vol % aqueous alcohol (80-90% helicity), it does not reach full helicity even in the solution containing excess amount of phospholipid liposome (maximum 65-70% helicity). The conformational difference is explained by the characteristic amphipathy of the peptide, i.e., the necessity to twist the separated amphipathic helical parts in the interaction with the phospholipid membrane probably makes the helicity of the peptide decrease.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360310707
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  • 2
    Electronic Resource
    Electronic Resource
    α-Helical assembly of biologically active peptides and designed helix bundle protein (1994)
    New York : Wiley-Blackwell
    Biopolymers 34 (1994), S. 481-488 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The formation of α-helical assembly by complexing biologically active peptides with de novo designed protein is described. The de novo designed protein described here is a cystinelinked 4-helix bundle protein constructed with 80 amino acid residues and forms a hydrophobic core region surrounded by 4 helices in an aqueous solution. The biologically active peptides, such as melittin and human growth hormone releasing factor, contain the sequences that are able to form amphiphilic helices. These peptides alone do not form the α-helix structure in a diluted solution with low ion strength. But on mixing with the designed helix bundle protein, the peptides are strongly bound to the protein with the induction of α-helical structure in the biologically active peptides. The content of induced α-helix is in accord with that estimated from the amphiphilic sequence. The results mean that a novel architecture composed of α-helices is formed. Fluorescent and temperature-scanning measurement revealed that the α-helical assembly is constructed with hydrophobic interaction. Also, it is shown by means of fluorescence depolarization that the assembly has a compact globular form corresponding to 1 : 1 complex. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360340405
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  • 3
    Electronic Resource
    Electronic Resource
    Biosynthesis of the Indole Alkaloids. Cell-free Systems from Catharanthus roseus PlantsFor preliminary reports of this work, see [1-4]. (1982)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 2088-2101 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cell-free systems from Catharanthus roseus plants are utilized for various studies relating to the biosynthesis of indole alkaloids. Tryptamine (5) and secologanin (6), two fundamental building units, are shown to be incorporated into the alkaloid vindoline (7). In another study, catharanthine (18) and vindoline (7) are utilized by this enzyme system and coupled to the important bisindole biointermediate 3′,4′-anhydrovinblastineThe previously [20] used name for 17, 3′, 4′-dehydrovinblastine, is incorrect. (17). The latter substance is, in turn, incorporated and converted to the natural alkaloids leurosine (8), Catharine (9) and vinblastine (10), thereby providing information about the biosynthesis of these complex molecules. High pressure liquid chromatography assay of the enzymic mixture sheds light on the enzymes involved in the coupling of 18 and 7.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19820650716
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  • 4
    Electronic Resource
    Electronic Resource
    Total Synthesis of Indole and Dihydroindole Alkaloids. XVIIIPart XVII: [1].. Isomers and analogues of vinblastine (1980)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 63 (1980), S. 366-374 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and conformational analysis of (3′R)-3-hydroxyleurosidine (5), (3′S)-3-hydroxyleurosidine (10), (3′S)-3-acetoxy-4′-deoxyleurosidine (15), (3′R)-3-acetoxy-4′-deoxyleurosidine (23), (3′R)-3-acetoxy-4′-deoxyvinblastine (16), (3′S)-3-acetoxy-4′-deoxyleurosidine (28) is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19800630206
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  • 5
    Electronic Resource
    Electronic Resource
    Direct polymerization of N-carboxy anhydride of L-glutamic acid (1981)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 2127-2137 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new method of polymerization of the N-carboxy anhydride (NCA) of glutamic acid is presented by which poly(glutamic acid) is obtained directly from the NCA without protecting its carboxyl group. The principle underlying is that by adjusting the mole ratio of the initiator butylamine, [I], to the monomer, [A], butylamine can be used as protecting agent for the carboxyl group of the NCA so that the rest of butylamine acts as initiator in the heterogeneous polymerization in acetonitrile. Quantitative conversion was obtained for an [A]/[I] ratio of 1. In analogy to other heterogeneous polymerizations of NCAs in acetonitrile, this is due to the formation of the helix during polymerization, which was confirmed by IR absorption and X-ray diffraction measurements. As the [A]/[I] ratio increases, the conversion, the helix content of the resultant polymer, and the amount of butylamine combined with it decrease drastically. It is suggested that “copolymerization” of the amine-protected and unprotected NCAs occurs, giving rise to a partially helical chain, whose contents of the amine-protected side chains and accordingly of the helix are the higher the smaller the [A]/[I] ratio.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1981.021820802
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  • 6
    Electronic Resource
    Electronic Resource
    Radical polymerization of 3-methylene-5,5′-dimethyl-2-pyrrolidinone: A cyclic analog of N-substituted methacrylamide (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 949-955 
    Details
    ISSN: 0887-624X
    Keywords: radical polymerization ; 3-methylene-5,5′-dimethyl-2-pyrrolidinone ; exomethylene cyclic monomers ; kinetics ; monomer reactivity ratios ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3-Methylene-5,5′-dimethyl-2-pyrrolidinone (α-MDMP), a cyclic analog of N-substituted methacrylamide, was synthesized and polymerized with α,α′-azobis (isobutyronitrile) (AIBN) in solution. Poly(α-MDMP) is only soluble in dimethyl sulfoxide (DMSO) at room temperature. Thermogravimetry of poly(α-MDMP) showed 10% weight loss at 355°C in air and 400°C under nitrogen, respectively. The kinetics of α-MDMP homopolymerization with AIBN was investigated in DMSO. The rate of polymerization (Rp) can be expressed by Rp = k[AIBN]0.49[α-MDMP]1.0 and the overall activation energy has been calculated to be 73.2 kJ/mol. Monomer reactivity ratios in copolymerization of α-MDMP (M2) with methyl methacrylate (M1) are r1 = 0.71 and r2 = 0.71, from which Q and e values of α-MDMP are calculated as 0.75 and -0.43, respectively. © 1993 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080310413
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  • 7
    Electronic Resource
    Electronic Resource
    Preparation of poly(aryleneethynylene)-type copolymers containing flexible linking methylene units. Optical properties of the copolymers suggesting occurrence of energy transfer between π-conjugated local units (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2201-2207 
    Details
    ISSN: 0887-624X
    Keywords: poly(aryleneethynylene) ; palladium-catalyzed ; copolymer ; optical properties ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Palladium-catalyzed polycondensation between 2,5-diiodo-3-hexylthiophene I-Th(Hex)-I with mixtures of p-diethynylbenzene HC≡C - Ph - C≡CH and α,ω-diethynylalkane HC≡C(CH2)lC≡CH (l = 3 or 8) gives poly(aryleneethynylene) PAE-type copolymers [C≡C(CH2)lC≡C - Th(Hex)]m[C≡C - Ph - C≡C - Th(Hex)]n containing the methylene unit. The copolymers have a molecular weight (Mn) of about 1.2 × 104 as determined by GPC (polystyrene standard) and are considered to possess essentially a random sequences in view of the  - C≡C(CH2)lC≡C -  and  - C≡C - Ph - C≡C -  units as judged from their UV-visible spectra. By the incorporation of the (CH2)l unit, the λmax position of the corresponding PAE homopolymer [C≡C - Ph - C≡C - Th(Hex)]n is shifted to a shorter wavelength. However, the copolymers give rise to a photoluminescence PL peak essentially agreeing with a PL peak of the homopolymer, suggesting occurrence of energy transfer in the copolymer. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2201-2207, 1998
    Additional Material: 3 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis and emulsion copolymerization of amphiphilic poly(2-oxazoline) macromonomer possessing a vinyl ester group (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 123-128 
    Details
    ISSN: 0887-624X
    Keywords: amphiphilic macromonomer ; poly(2-oxazoline) ; emulsion copolymerization ; vinyl ester group ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The present article describes the synthesis and emulsion copolymerization of a block-type amphiphilic poly(2-oxazoline) macromonomer possessing a polymerizable vinyl ester group. The macromonomer was synthesized by one-pot two-stage block copolymerization of 2-oxazolines using vinyl iodoacetate as initiator. 2-Methyl- and 2-n-butyl-2-oxazolines were employed for the construction of hydrophilic and hydrophobic segments, respectively. The surface activities evaluated by the surface tension of the macromonomer in water were fairly good. Emulsion copolymerization of vinyl acetate with the macromonomer was carried out. The macromonomer acted as a polymeric surfactant, as well as a comonomer. The resulting copolymer latex particles were spherical and their diameter was in the sub-micron range. The effects of the composition of the macromonomer on the emulsion copolymerization and the resulting latex particles were examined. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080310114
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  • 9
    Electronic Resource
    Electronic Resource
    Separation of water-ethanol by pervaporation through polyion complex composite membranePaper presented at 3rd International Conference on Pervaporation Processes in the Chemical Industry, September 1922, Nancy, France. (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 3229-3239 
    Details
    ISSN: 0021-8995
    Keywords: 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 , Physics
    Notes: For the purpose of separating alcohol-water mixtures by the use of the pervaporation technique, new composite membranes composed of polyion complexes (PIC) as a separating layer were developed. The polyion complex structure, consisting of polyacrylic acid (PAA) and polycation, provided excellent permeation rate and selectivity. Among the polycations, ionenes, which have quaternary ammonium groups in the backbone chain, were effective in giving membranes of higher permselectivities. High selectivity of PIC membranes was observed at high ethanol concentration regions in the feed mixture. For the azeotropic mixture of water/ethanol (95 wt % EtOH) at 60°C, the PAA-based PIC membrane had the following separation properties: separation factor ∼ 3,500 and permeation rate ∼ 1.6 kg/m2 h.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070421216
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  • 10
    Electronic Resource
    Electronic Resource
    Two-stage drawing of poly(ethylene 2,6-naphthalate) (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 1013-1023 
    Details
    ISSN: 0021-8995
    Keywords: 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 , Physics
    Notes: Initially amorphous and semicrystalline films of poly(ethylene 2,6-naphthalate) with different molecular weights were drawn by two-stage drawing, that is, coextrusion at low temperatures (25-160°C) followed by tensile drawing at high temperatures (200-245°C). Both films could be drawn up to a draw ratio of 8-10 by this method under controlled conditions. The tensile modulus and strength of drawn samples were greatly affected by the draw temperature for the first stage, predrawn morphology, and molecular weight. The remarkable effects of these variables on the tensile properties are closely related to the difference in the resultant amorphous chain orientation of the samples, reflecting the disentanglements and chain slippage during drawing, and the dissipation of chain orientation after processing.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070460609
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