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  • 1
    Electronic Resource
    Electronic Resource
    The hinge-bending mode of a lysozyme-inhibitor complexSupported in part by a grant from the National Institutes of Health. (1986)
    New York : Wiley-Blackwell
    Biopolymers 25 (1986), S. 1767-1802 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hinge-bending mode of hen egg white lysozyme is studied by a constrained minimization technique. Results with and without a bound inhibitor, tri-N-acetyl-glucosamine, are obtained. The frequency of the mode with the inhibitor is found to be 4.3 cm-1, in contrast to 3.0 cm-1 for the free enzyme. Also, the hinge-bending angle with the lowest energy is shifted 10° towards a more closed cleft in the bound species. The main contribution to these differences arise from interactions with the residues lining the cleft and those on the back side of it. Structural details that account for the energetics are presented. The method of calculation is somewhat different from a previous study [J. A. McCammon, B. R. Gelin, M. Karplus & P. G. Wolynes, (1976) Nature 262, 325-326] to reduce the likelihood of artifacts in the results.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360250916
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  • 2
    Electronic Resource
    Electronic Resource
    Prediction of the folding of short polypeptide segments by uniform conformational sampling (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 137-168 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A procedure, CONGEN, for uniformly sampling the conformational spaceof short polypeptide segments in proteins has been implemented. Because thetime required for this sampling grows exponentially with the number of residues, parameters are introduced to limit the conformational space that has to be explored. This is done by the use of the empirical energy function ofCHARMM [B. R. Brooks, R. E. Bruccoleri, B. D. Olafson, D. J. States, S. Swaminathan and M. Karplus (1983) J. Comput. Chem. 4, 187-217] and truncating the search when conformations of grossly unfavorable energy are sampled. Tests are made to determine control parameters that optimize the search without excluding important configurations. When applied to known protein structures, the resulting procedure is generally capable of generating conformations where the lowest energy conformation matches the known structure within a rms deviation of 1 Å.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260114
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  • 3
    Electronic Resource
    Electronic Resource
    Notiz zur Synthese Eines Optisch Aktiven Ace-Hemmers mit Amino-oxo-benzazepin-1-alkansäure-Struktur mittels enantiokonvergierender kristallisationsinduzierter Racemat-Trennung (1988)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 71 (1988), S. 337-343 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Note on the Synthesis of an Optically Active ACE Inhibitor with Amino-oxo-benzazepine-1-alkanoic-Acid Structure by Means of an Enantioconvergent Crystallization-Based ResolutionAn enantioselective synthesis of the potent angiotensin-converting enzyme inhibitor (1′S,3S)-3-[(1′-(ethoxy-carbonyl)-3′-phenylpropyl)amino]-2,3,4,5-tetrahydro-2-oxo-1H-1-benzazepine-1-acetic acid hydrochloride (3) is described which user a crystallization-based resolution of a racemic amino intermediate with concomitant racemization of the unwanted enantiomer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19880710205
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  • 4
    Electronic Resource
    Electronic Resource
    Diels-Alder Approach to Highly Functionalized Tertiary α-Hydroxy Ketones: A Novel Route to the Hexahydrobenzofuran Portion of the Avermectins and Milbemycins (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1273-1286 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A highly regio- and stereoselective Diels-Alder reaction between dienophiles of type I and dienes of type II (Scheme 1) gives rise to Diels-Alder adducts of type III. Upon treatment with BF3.Et2O, these adducts are smoothly converted into the corresponding enones (Scheme 6). Under mild acidic conditions, enone (±)-33 gave bicyclic diketone (±)-34 via an intramolecular Michael-type addition. Diketone (±)-34 has the correct relative configuration and a suitable ketone function at C(6) for further conversion into the hexahydrobenzofuran portion of the avermectins and milbemycins.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690602
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  • 5
    Electronic Resource
    Electronic Resource
    Tg-Composition analysis of miscible polymer blends (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1355-1361 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Several authors have suggested a monotonic variation of the glass transition temperature (Tg) of miscible polymer blends as a function of composition. They usually express the results in terms of equations proposed by Couchman-Karasz, Gordon-Taylor, Fox, and several others. However, we have noticed that numerous systems exhibit a cusp when Tg is plotted as a function of composition (after correction for the presence of crystallinity when semi-crystalline polymers are involved). This cusp cannot appear when the Tg's of the two homopolymers involved are separated by less than about 52 degrees., It will be shown that this observation is quite general since it has been observed with several polyester/chlorinated polymer blends, polycaprolactone/nitrocellulose blends, and polystyrene/poly(vinylmethylether) blends; It will also be shown that this behavior is predicted in the framework of the free volume theory, with equations derived by Kovacs. According to this theory, above a critical concentration φc (relative to the plasticizer) and below a critical temperature Tc, the high-Tc, polymer no longer contributes to the free volume of the mixture whereas it does above Tc. This difference leads to a Tg-composition variation which has to be expressed by two different equations, one below Tc and the other above Tc, the cusp defining the limit of applicability of each equation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760282104
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  • 6
    Electronic Resource
    Electronic Resource
    Electric field effects on a liquid-crystalline side chain polymer with a negative dielectric anisotropy (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 2407-2414 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The behavior of methacrylic side chain polymers in an electric field was observed for a homopolymer (1) exhibiting a negative dielectric anisotropy compared with a copolymer (2) of positive dielectric anisotropy. Homopolymer 1 orients spontaneously homeotropic and thus enables the determination of the threshold voltage, rise time and decay time. Based on these experimental results the bend elastic constant and viscosity coefficient were estimated using literature values for the dielectric anisotropy. With respect to the bend elastic constant and electrohydrodynamic effects (e.g. Williams Domains) the homopolymer behaves similarly to low-molar-mass liquid crystals, while owing to the high viscosity coefficient response times are large in magnitude.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021861121
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  • 7
    Electronic Resource
    Electronic Resource
    Morphology of nylon 6 spherulites in bulk (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1195-1204 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A method of obtaining good quality ultrathin sections from nylon 6 bulk samples has been developed by using a special embedding technique and cryo-ultramicrotomy. The morphologies of nylon 6 processed by compression and injection molding and of reaction injection molded nylon 6 were studied in ultrathin sections of bulk samples by means of transmission electron microscopy. It was established that the spherulites of nylon 6 in bulk are built up from long flat ribbonlike lamellae. The thickness of the lamellae is in the range 50-60 Å. The width varies from 150 to 600 Å and depends on the type of nylon 6 and the method of processing. The length of the lamellae is relatively large approaching spherulite radii, extending often from the point of their origin up to the spherulite borders. Three or four neighboring lamellae within spherulites usually show similar orientation of their flat faces and form domains which can easily be mistaken for fibrils in light microscopy or low resolution electron microscopy.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880522
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  • 8
    Electronic Resource
    Electronic Resource
    Black crazes  -  white crazes? (1986)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 431-439 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The origin of the curious “inverted contrast” often observed in transmission electron micrographs of crazes in rubber-toughened thermoplastics was determined by using scanning transmission electron microscopy with X-ray fluorescence analysis. The “black crazes” seen in the micrographs contain high concentrations of osmium metal which is introduced through OsO4 used to stain the rubber phase. Treatment of stained sections with a strong oxidizing agent (NaIO4) removes a sufficient amount of osmium to reveal the commonly observed tufty craze microstructure with the expected contrast of light crazes in a darker background.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1986.021870222
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  • 9
    Electronic Resource
    Electronic Resource
    Spatial organization of homopolymer chains inside spherical polybutadiene domains of styrene-butadiene diblock copolymersDedicated to Dr. Paul Rempp on the occasion of his 60th birthday (1989)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 190 (1989), S. 589-598 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Blends of perdeuterated polybutadiene and a styrene-butadiene diblock copolymer (polystyrene-block-polybutadiene) were prepared by solution-casting techniques. Small-angle neutron scattering and transmission electron microscopy experiments on blends containing homopolymer with chain length smaller than the corresponding block sequence showed that homopolymer chains are solubilized by the spherical microdomains up to a homopolymer content of about 15 mol-percnt;. The solubilized homopolymer is distributed in a spatially uniform manner throughout the domain volume and the radius of gyration of the homopolymer is only slightly larger than that of an unperturbed chain in bulk. At about 18 mol-percnt;, pools of homopolymer appear outside the microdomains; the change in scattering intensities indicates that pool formation is a kinetic phenomenon rather than a thermodynamically controlled event. Experiments on blends containing longer homopolymer chains revealed a lower concentration, between 3 and 6 mol-percnt;, for the onset of homopolymer pool formation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1989.021900315
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  • 10
    Electronic Resource
    Electronic Resource
    Subunit assembly and metabolic stability of E. coli RNA polymeraseThis is paper No. 10 in the series entitled “Subunit of RNA polymerase in Function and Structure.” Paper No. 9 is ref. 65. (1987)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 2 (1987), S. 42-53 
    Details
    ISSN: 0887-3585
    Keywords: proteolytic cleavage ; immunological cross-reaction ; amber fragment ; temperature-sensitive mutant ; stationary growth-phase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Immunological cross-reaction was employed for identification of proteolytic fragments of E. coli RNA polymerase genered both in vitro and in vivo. Several species of partially denatured but assembled RNA polymerase were isolated, which were composed of fragments of the two large subunits, β and β′, and the two small and intact subunits, α and σ. Comparison of the rate and pathway of proteolytic cleavage in vitro of unassembled subunits, subassemblies, and intact enzymes indicated that the susceptibility of RNA polymerase subunits to proteolytic degradation was dependent on the assembly state.Using this method, degradation in vivo was found for some, but not all, of the amber fragments of β subunit in merodiploid cells carrying both wild-type and mutant rpoB genes. Although the RNA polymerase is a metabolically stable component in exponentially growing cells of E. coli, degradation of the full-sized subunits was found in two cases, i.e., several temperature-sensitive E. coli mutants with a defect in the assembly of RNA polymerase and the stationary-phase cells of a wild-type E. coli. The in vivo degradation of RNA polymerase was indicated to be initiated by alteration of the enzyme structure.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340020106
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