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  • National Academy of Sciences  (89)
  • Wiley-Blackwell  (74)
  • American Physical Society (APS)
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  • 1
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    1-Phosphatidylinositol 3-kinase activity is required for insulin-stimulated glucose transport but not for RAS activation in CHO cells. (1994)
    National Academy of Sciences
    Details
    Publication Date: 1994-08-02
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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    PAPER CURRENT
  • 2
    Electronic Resource
    Electronic Resource
    Physicochemical properties of (1 → 6)-branched (1 → 3)-β-D-glucans. 1. Physical dimensions estimated from hydrodynamic and electron microscopic data (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 561-573 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The physical dimensions of several (1 → 6) branched (1 → 3) -β-D-glucan samples obtained from different organisms and their derivatives have been studied by electron microscopy, light scattering measurements, viscometry, and gel permeation chromatography. The electron micrographs indicate that in most samples these biopolymers are adequately described as linear worm-like coils. A sample reconstituted from alkaline media appeared as a blend of the linear, circular, and aggregated polymer morphologies. The average mass per unit length, ML = Mw/Lw for the macroscopically linear samples, was estimated to be 2100 ± 200 g mol-1 nm-1. The parameter mL was determined from the contour lengths obtained by electron microscopy and the molecular weight by light scattering measurements. The observed ML was consistent with the triple-helical structure reported from x-ray diffraction studies and observed degree of side-chain substitution. From the molecular snapshots shown in the electron micrographs, the persistence lengths of these β-D-glucans were determined to be 140 ± 30 nm. The experimentally determined intrinsic viscosities were consistent with these estimates of ML and persistence length. Comparison of the molecular weight distributions obtained from gel permeation chromatography and those deduced from the electron micrographs indicates that number and weight average contour lengths are more reliable than z and z + 1 averages. © 1993 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360330406
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  • 3
    Electronic Resource
    Electronic Resource
    Macromolecular cyclization of (1 → 6)-branched-(1 → 3)-β-D-glucans observed after denaturation-renaturation of the triple-helical structure (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 193-198 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360330118
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  • 4
    Electronic Resource
    Electronic Resource
    Study of polysaccharides by the fluorescence method. III. Chain length dependence of the micro-Brownian motion of amylose in an aqueous solution (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1043-1056 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fluorescence polarization method was applied to the investigation of the micro-Brownian motion of amylose chains having a wide range of degree of polymerization (DP). We prepared two types of fluorescent conjugates of amylose: amylose conjugated with fluorescein randomly throughout the chain (F-amylose) and amylose conjugated locally on a terminal segment (t-F-amylose). The degree of fluorescence polarization of these conjugates was measured by changing the solvent viscosity at a constant temperature (25°C). The data obtained were analyzed by a Perrin-type equation to calculate the mean rotational relaxation time, 〈ρ〉. By examination of the plots of 〈ρ〉 vs DP, and by comparison of 〈ρ〉 with the theoretical rotational relaxation time of the whole molecule at a given DP, it was found that 〈ρ〉 mainly reflects the segmental motion of the amylose chain in the high-DP range. Thus, the fact that 〈ρ〉 for t-F-amylose is much smaller than that for F-amylose at a sufficiently high DP shows that a terminal segment undergoes a more rapid micro-Brownian motion than interior segments. In the low-DP range, we felt that the rotational diffusion of the whole molecule contributes significantly to the relaxation process. We also examined, for comparison, the segmental motion of dextran and pullulan in a similar manner and found that these segmental motions are more rapid than those of amylose. Based on the results obtained, the segmental mobility and conformation of the amylose molecule are discussed in relation to its chain length.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230606
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  • 5
    Electronic Resource
    Electronic Resource
    Locally oscillatory motion of RNA helix derived from linear relationships of backbone torsion angles (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1169-1184 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A linear relationship in each of the torsion angle pairs, α-β, β-∊, ∊-ζ, and α-γ, has been found by applying a statistical method based on the concept of circular variates to backbone torsion angle data of helical in yeast tTNAPhe. A series of helical dimer models generated with these relationships have been found to be stereochemically acceptable, and the models also indicate that the backbone unit in the RNA helix is geometrically capable of an oscillatory motion with the distance of about 3.4 Å between adjacent bases. The motion of the backbone unit is analogous to that of a helical spring. The adjacent bases, because of being attached to the backbone, oscillate in a manner similar to the oscillatory dimer model proposed by Davis and Tinoco [Davis, R. C. & Tinoco, I., Jr. (1968) Biopolymers 6, 223-242]. Here, the oscillation of the backbone unit in the RNA helix is discussed in terms of two geometrical quantities: the torsion (τ) and curvature (κ) of the helix. On these lines, a stereochemical model of RNA strand separation is proposed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230703
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  • 6
    Electronic Resource
    Electronic Resource
    A Monte Carlo study of the excluded-volume effect on the amylosic chain conformation (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 537-548 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Monte Carlo procedure was used to determine the effect of excluded volume on the conformational dimensions of amylosic chains. The excluded volume was introduced into the model by assuming that hard spheres, which cannot overlap each other, exist at the center of mass of each glucose unit in the chain sequence. Monte Carlo chains, which were generated to be distributed consistent with the potential energy of nonbonded nearest-neighbor interactions, underwent self-intersections, and the attrition rate in the generation of self-avoiding chains was found to obey an exponential decay law with increasing chain length x. Thus, in order to generate effectively a large number of self-avoiding chains with long sequences, we used the Wall-Erpenbeck s-p method of chain enrichment [F. T. Wall and J. J. Erpenbeck (1959) J. Chem. Phys. 30, 634-637]. By examination of the radial distribution of the end-to-end distance and the chain-length dependence of the quantity 〈r2〉/xl2 (〈r2〉 is the mean square end-to-end distance and l is the virtual bond length), it was found that unperturbed amylosic chains change in overall conformation from a non-Gaussian chain having a helical character to Gaussian as x is increased, whereas perturbed chains do not show Gaussian behavior even at x = 500. For the perturbed chains, 〈r2〉 can be expressed by the equation 〈r2〉 = axb in the range of 100 ≤ x ≤ 500, where a and b 〉 1 are constants. From comparisons of the persistence vectors and perspective drawings of representative unperturbed and perturbed chains, we felt the local conformation of the amylosic chains, i.e., the local helical character, is also affected by the long-range excluded-volume interaction.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260407
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  • 7
    Electronic Resource
    Electronic Resource
    Conformational analysis of chitobiose and chitosan (1994)
    New York : Wiley-Blackwell
    Biopolymers 34 (1994), S. 203-208 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relaxed potential energy surfaces of chitobiose were calculated based on the MM3-force field by optimizing dimer structures on a 10° grid spacing of the torsional angles about the glycosidic bonds (Φ,Ψ). The 36 conformations; the four combinations of the hydroxymethyl group orientations coupled with the nine of the secondary group ones -  were assumed for each Φ,Ψ conformation. The four conformations, each differing in the hydroxymethyl group orientations, were considered for the whole Φ,Ψ space, and all the 36 conformations, for the restricted space of low energy. While the resulting energy map and the structures of the energy minima were similar to those proposed for cellobiose in many respects, more restricted energy profile was suggested for the relaxed map of chitobiose where differences in the energy level between the global minimum and the local minima were within 5.4 kcal/mol, compared with the equivalent value of 3.6 kcal/mol for cellobiose. Further depression of the global minimum occurred when the acidic residue was used. The Monte Carlo samples of the chitosan chain were generated based on the relaxed map to predict the unperturbed coil dimension in solution. The chitosan chains showed Gaussian behavior at x = 500 (x, degree of polymerization) and gave the characteristic ratio Cx, of about 70, which was much larger than the experimental values observed for the chitosan and cellulosic chains. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360340206
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  • 8
    Electronic Resource
    Electronic Resource
    Functional metal porphyrazine derivatives and their polymers, 14Part 13: O. Hirabaru, T. Nakase, K. Hanabusa, H. Shirai, K. Takemoto, N. Hojo, Polym. Commun. in the press.. Synthesis and properties of [bis- or tetrakis(decyloxycarbonyl)phthalocyaninanto]metal complexes (1984)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 185 (1984), S. 2537-2542 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A novel class of [bis- and tetrakis(decyloxycarbonyl)phthalocyaninato]metal complexes (metal = Fe(III), Co(II), Ni(II), or Cu(II)) (6a, b and 2a - d) was synthesized by condensation of the corresponding acid chloride derivatives (5 and 1) with 1-decanol. The electrical conductivities of polystyrenes, containing these complexes as dispersions, were measured.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1984.021851206
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  • 9
    Electronic Resource
    Electronic Resource
    Mechanical denaturation of high polymers in solutions, 34Part 33: cf.10.Dedicated to Professor Dr. Yūkichi Go on his 77th birthday.. Nucleation and growth of poly(vinyl alcohol) crystals from flowing solution (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 2009-2018 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The nucleation and growth of the crystals of poly(vinyl alcohol) (PVA) from its solution keeping in contact with air under steady-state flow were investigated. The nucleation was considered to occur close to the solution surface because of the adsorption of PVA molecules to the solution surface. It was ascertained by the following results. The initial fibrillar crystal appeared under the solution surface after a few seconds of stirring. From the measurement of the surface tension of PVA solutions, PVA molecules were recognized to be adsorbed to the solution surface in a very short time. The random coil of PVA molecule cannot be extended and oriented in a solution stirred under steady-state flow with a shear rate below 5.103 s-1 applied in this experiment. This was concluded from an evaluation of the chain extension in a velocity gradient in shearing flow using the dumbbell model. The propagation of the precipitate is accelerated by turbulent flow induced by the flow of the solution itself, foams and precipitates.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.021800815
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  • 10
    Electronic Resource
    Electronic Resource
    Copolymerization of vinyl chloride with trans-1,2-dichloroethylene (1965)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 9 (1965), S. 1669-1680 
    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: Copolymerization of vinyl chloride with trans-1,2-dichloroethylene was carried out at various temperatures, and the properties of the copolymers obtained by the emulsion copolymerization at low temperature were examined. In the case of bulk copolymerization at temperatures higher than room temperature, the rate of polymerization, the equilibrium conversion, and [η] were lowered with increasing content of trans-1,2-dichloroethylene in the initial monomer mixture, but the Tg and softening point of the copolymers containing about 15% of 1,2-dichloroethylene unit were about 10°C. higher than these of conventional PVC resin, in spite of their inability to form films. The monomer reactivity ratios at 50°C. were 5.39 (VC) and 0.072 (trans-DCE). Emulsion copolymerization was carried out at -30°C. with the use of a redox initiator system (hydrogen peroxide-ferrous sulfate-ascorbic acid), in order to increase both the [η] and the rate of polymerization. The copolymers prepared at low temperature had higher Tg and better solubility than the VC homopolymer polymerized at the same condition or conventional PVC resin. The results of the infrared absorption spectra, the solubilities, and the calculation of sequence length of VC monomer unit in the polymer chain indicated that the stereoregularity and the crystallinity of the low temperature copolymers were lower than those of the low temperature VC homopolymers. It was concluded that higher Tg and good solubility of the low temperature copolymer were brought about by the prevention of the free rotation of the polymer chain by the random distribution of 1,2-dichloroethylene units in the polymer chain.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1965.070090506
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