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  • Polymer and Materials Science  (9)
  • 1970-1974  (9)
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  • 1
    Electronic Resource
    Electronic Resource
    Configurational statistics of polysaccharide chains. Part II. CelluloseContribution No. 286 from Centre of advanced study in physics, University of Madras, India. (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 783-790 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The characteristic ratio of unperturbed cellulose chain was computed as a function of the angle τ at, the bridge oxygen atom and the degree of polymerization. Very high values of the order of 40 or more, depending on the angle at the bridge oxygen atom, have been obtained for this ratio, indicating that cellulose chains are highly extended. The average dimensions of cellulose chains are found to be sensitive even for small changes in the angle at the bridge oxygen, and these chains attain the character of a random coil in very high molecular weight range (degree of polymerization greater than 2000). The large differences in the unperturbed dimensions of cellulosic chains observed in different solvents have been attributed to the possible small changes in the angle τ caused by specific solvent, interactions.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1970.360090704
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  • 2
    Electronic Resource
    Electronic Resource
    Conformational studies of linear β-D-1,4′-mannan and galactanContribution No. 289 from the Centre of Advanced Study in Physics, University of Madras, Madras, India. (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1239-1247 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The nonbonded interaction energy of disaccharides, mannobiose and galactobiose and polysaccharides mannan and galactan have been computed as a function of dihedral angles (φ,ψ). The conformation (40°, -20°) has been preferred for the mannan chain from nonbonded interaction energy considerations. The O5…O3′ type of intramolecular hydrogen bond has been found to be possible in the above conformation. Comparison of the allowed region of mannan with those of cellulose and xylan indicates that the monomer unit, in mannan chain has slightly higher freedom of rotation than that of cellulose and less than that of xylan. As in cellulose and mannan, the freedom of rotation of the monomer units in β-1,4′ galactan is highly restricted. Unlike mannan (which prefers an extended conformation) the β-1,4′ galactan prefers a helical conformation similar to amylose. Just as in amylose the O2…O3′ type hydrogen bond between contiguous residues is also possible in β-1,4′ galactan.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1970.360091004
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  • 3
    Electronic Resource
    Electronic Resource
    Conformational studies of α-glucansContribution No. 345 from the Centre of Advanced Study in Physics, University of Madras, Madras, India. (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1379-1394 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A study of the effect of linkage on the possible conformations of di-and polysaccharides of α-D-glucose and also the probable intramolecular hydrogen bonds has been made. The differences in the nature of linkage is shown to effect the energetically preferred conformations; (1 → 2) linkages lead only to righthanded helical conformations, (1 → 3) linkages lead to extended as well as both left and righthanded helical conformations; (1 → 4) linkages lead to both right-and lefthanded wide helical conformations. The possible hydrogen bonds between adjacent residues are also dependent on the nature of the linkage. A comparison of the conformational data of α-D-glucans with those of β-D-glucans has indicated that the favored conformations and hydrogen bonds between contiguous residues in the chain are influenced by the configuration at the anomeric carbon atom in all the three types of polysaccharides. From the energy calculations a probable conformation (φM = -10°, ψM = -30°, φN = -23°, ψN = -19°) has also been proposed for crystalline mycodextran in conformity with x-ray data. This conformation contains two types of hydrogen bonds between contiguous residues one between 0-2 and 0-3 atoms at (1 → 4) linkage and the other between 0-2 and 0-4 atoms at (1 → 3) linkage in the chain. The conformation of maltose unit (-10°,-30°) that is likely to occur in the crystalline mycodextran coincides with the minimum energy conformation of maltose.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1972.360110707
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  • 4
    Electronic Resource
    Electronic Resource
    Configurational statistics of polysaccharides. VI. Linear (1→4)-linked galactanPart of this work was presented at the American Chemical Society Meeting, Los Angeles, California, April 1971, as Contribution No. 341 from Centre of Advanced Study in Physics, University of Madras, Madras, India. (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 10 (1972), S. 1369-1382 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The conformational energies for (1→4)-linked α-D- and β-D-galactans have been computed by considering nonbonded, torsional, and electrostatic interactions. The electrostatic interactions are estimated by assigning the charges to various atoms in the molecule by the method of Del Re. The characteristic ratios CN = 〈r2〉0/Nlv2 are computed for α-D- and β-D-galactans as a function of the degree of polymerization N and the angle τ at the bridge oxygen atom. These values of characteristic ratios obtained for α-D-galactan are very much higher than for β-D-galactan, indicating that the former assumes a highly extended conformation compared to the latter. The values of characteristic ratios of both these polysaccharides show a decrease with increase in τ similar to that observed for other (1→4)-linked polysaccharides. The calculated values of C∞ of (1→4)-linked polysaccharides show no correlation with the number of allowed conformations but are affected both by the orientation of the interunit glycosidic bonds and the hindered potential associated with chain units. It has also been shown that the magnitude of the steric factor σ may not be used as an index of flexibility for polysaccharides which differ in type of linkage.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1972.160100715
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  • 5
    Electronic Resource
    Electronic Resource
    Configurational statistics of polysaccharides. V. Free rotational dimensions of (1 → 2′)-, (1 → 3′)-, and (1 → 4′)-linked polysaccharides (1971)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 1149-1151 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1971.160090611
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  • 6
    Electronic Resource
    Electronic Resource
    Conformation of random polypeptide chains (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 10 (1972), S. 693-697 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The characteristic ratios Cof and C∞ are calculated for infinitely long poly(L-amino acid) chains having a—CH2—R′ substitution at the Cα atom, as functions of the valence angle τ at the Cα atom. The value of Cof is found to increase from 1.6 to 2.3 as τ varies from 105 to 115°. On the other hand, C∞ decreases with increasing τ in the range 105-111°, passes through a minimum at 111°, and then increases slowly. Since, C∞ is much less dependent on τ in the most commonly observed range (110-115°), any variation in τ in this range due to solvent would not appreciably affect C∞. The calculated temperature coefficient of C∞ is negative and increases significantly in absolute magnitude even for small deviations in τ from 110°.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1972.160100411
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  • 7
    Electronic Resource
    Electronic Resource
    Configurational statistics of polysaccharide chains. Part III. Linear β-(1 → 4′) xylan and mannanContribution No.320 from the Centre of Advanced Study in Physics, University of Madras, Madras-25, India (1971)
    New York : Wiley-Blackwell
    Biopolymers 10 (1971), S. 1891-1900 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The characteristic ratio CN = 〈r2〉0/Nlv2 of the β-D(1 → 4′)-linked polysaccharides xylan and mannan has been computed as a function of the angle τ at the bridge oxygen atom and the degree of polymerization N. The calculated values of the characteristic ratio CN are very high relative to their free rotational dimensions. The characteristic ratio of these polysaecharides converges to the asymptotic value at low degree of polymerization at higher τ values. The low values of the calculated characteristic ratio of xylan compared to cellulose and mannan for the same τ value indicate that the former is more flexible and assumes a compact configuration. A pronounced difference in the values of the characteristic ratio CN of cellulose and mannan has also been observed lower τ angles (〈120°). On the other hand, nearly the same values of CN have been obtained at higher τ angles (120°-125°), which suggests that, cellulose and mannan may have similar configuralons in certain solvents.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360101010
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  • 8
    Electronic Resource
    Electronic Resource
    Conformational studies of β-glucans (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1115-1115 
    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.1972.360110513
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  • 9
    Electronic Resource
    Electronic Resource
    Conformation of cellulosic chains - part IVContribution No. 299 from the Centre of Advanced Study in Physics, University of Madras, Madras-25; India. (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 2033-2034 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160081116
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