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  • 1
    Electronic Resource
    Electronic Resource
    A 13C NMR study of cyclic dipeptides cyclo(-L-Ala-L-Ala-) and cyclo(-L-Ala-D-Ala-) in the solid state by cross polarization-magic angle spinning method (1984)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 5 (1984), S. 799-804 
    Details
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1984.030051204
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  • 2
    Electronic Resource
    Electronic Resource
    A 13C-NMR study on the conformational and dynamical properties of a cereal seed storage protein, C-hordein, and its model peptides (1997)
    New York : Wiley-Blackwell
    Biopolymers 41 (1997), S. 289-300 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have recorded the 13C CP-MAS and DD-MAS nmr spectra of dry and hydrated barley storage protein, C-hordein, as a model for wheat S-poor prolamins, together with those of model synthetic peptides (Pro)2(Gln)6(I) and (Pro-Gln-Gln-Pro-Phe-Pro-Gln-Gln)3(II) under dry or hydrated conditions. The spectral features of C-hordein as well as these peptides were appreciably different from each other depending on the extent of hydration, reflecting different domains that adopt different types of conformations as well as dynamics. In particular, considerable proportions of the peak intensities were lost in the CP-MAS spectra, and well-resolved 13C-nmr signals emerged in DD-MAS nmr spectra owing to acquisition of molecular motions by swelling. It was shown that local β-turn or (Pro)n type II conformation is more preferable for individual Pro residues and β-sheet type conformation is dominant for individual Gln residues in the dry and hydrated systems. In addition, two types of Gln environments are originated in C-hordein that differ in their mobility. Further, 13C spin-lattice relaxation times (T1's) of C- hordein and peptide II were reduced by more than one order of magnitude by hydration, reflecting the presence of well-swollen molecular chains. In contrast, theT1 values of peptide I upon hydration remained one third of those in the dry state. Carbon-resolved proton spin-lattice relaxation times in the rotating frame (T1ρ's) were also decreased by about 50% upon hydration, although these parameters were less sensitive as compared to T1 values. In addition, the 13C-nmr signals of the aromatic side chain of Phe residues disappeared on hydration owing to interference between the frequency of the acquired flip-flop motion and the proton decoupling frequency. This information gives a new insight into establishing the structural properties of the studied protein system. A model may be put forward for a gel-type structure in which the more rigid part of the system involves intermolecular hydrogen-bonded Gln side chains as well as some hydrophobic “pockets” involving Pro and Phe residues. The liquid-like domain is characterized by considerable backbone and side-chain motion as well as rapid ring-puckering motion in Pro residues. © 1997 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    High-Resolution solid-state 13C-nmr of peptides: A study of chain-length dependence for 310-helix formation (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 1607-1617 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High-resolution solid-state 13C-nmr spectra of two series of fully protected oligopeptides, Z-(Aib)n-OMe (n = 3-8) and Z-(Aib)n-L-Leu-(Aib)2-OMe (n = 0-5), were recorded to gain insight into main-chain length dependence for 310-helix formation. We found that all the oligopeptides examined adopt an incipient or a fully developed 310-helical structure, as judged from the characteristic splitting of the Cβ signals as well as the conformation-dependent displacements of the Cα and C=O peaks.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360271006
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  • 4
    Electronic Resource
    Electronic Resource
    Distinct gelation mechanism between linear and branched (1 → 3)-β-D-glucans as revealed by high-resolution solid-state 13C NMR (1990)
    New York : Wiley-Blackwell
    Biopolymers 29 (1990), S. 1689-1698 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have recorded high-resolution 13C-NMR spectra of linear (curdlan) and branched (lentinan, HA-β-glucan and its polyol and aldehyde derivatives) (1 → 3)-β-D-glucans in hydrate and gel states, in order to gain insight into their gelation mechanism. Network structure of curdlan turned out to be highly heterogeneous from its motional state, from liquid-like, through intermediate, to solid-like domains. They are studied by a variety of experiments, conventional high-resolution NMR by broad-band decoupling, high-power decoupling with magic angle spinning (MAS), and cross-polarization-magic-angle-spinning (CP-MAS). Nevertheless, we found that conformations of these distinct liquid-like and solid-like do- mains exhibit an identical single helix conformation with a small proportion of a triple helix form, supporting our previous view as to the gelation mechanism. In contrast, the network structure of branched (1 → 3)-β-D-glucans in the gel state arises mainly from the triple helix conformation. This means that gelation of branched (1 → 3)-β-D-glucan proceeds from partial association of the triple helical chains, previously proposed for gelation of a linear glucan. Furthermore, we found that conversion from the single chain to the single helix was not achieved readily by hydration of over 8h at 96% R. H. for branched glucan but the triple helix form is obtained when these samples are hydrated fully as in gel state.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360291402
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  • 5
    Electronic Resource
    Electronic Resource
    Evidence of three distinct conformations - single chain, single helix, and triple helix - of (1 → 3)-β-D-xylan in the solid and intact frond of green algae as studied by 13C-nmr spectroscopy (1991)
    New York : Wiley-Blackwell
    Biopolymers 31 (1991), S. 933-940 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High-resolution solid-state 13C-nmr spectra of (1 → 3) -β-D-xylan from Bryopsis maxima and Caulerpa brachypus were recorded for various preparations from intact through dried frond to anhydrous and hydrated xylan, to gain insight into their secondary structures as compared with those of (1 → 3)-β-D-glucans. It turned out that 13C-nmr peaks of intact or dried frond were mainly ascribed to the peaks from (1 → 3)-β-D-linked xylose residue, although some peaks were seen at the carbonyl and aliphatic regions. Dehydration of frond by either air drying or ethanol, and extraction of xylan with acid, did not result in substantial spectral change, although extraction with saturated ZnCl2 solution caused appreciable displacements of the C-3 as well as C-2 and C-5 peaks. This means that no major conformational change was induced during the above-mentioned processes of the dehydration and the extraction with acid. The extraction with ZnCl2 solution, however, induced major conformational change. Thus, we found that the above-mentioned three distinct conformations-triple helix, single helix, and single chain-are also present in (1 → 3)-β-D-xylan, as judged from the conformation-dependent displacements of 13C chemical shifts, hydration/dehydration-induced spectral change, and the x-ray diffraction data on Penicillus dumetosus by Atkins et al. In particular, we found that all the preparations except for the extraction with ZnCl2 solution retain the triple helix form, whereas the anhydrous and hydrate samples of the latter preparations take the single-chain and single-helix form, respectively. Further, we measured the 13C spin-lattice relaxation times of laboratory frame of the xylan to gain insight into better understanding of the role of the hydroxymethyl group as an efficient relaxation pathway in (1 → 3)-β-D-glucan.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360310803
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  • 6
    Electronic Resource
    Electronic Resource
    13C-nmr chemical shift and conformation of L-alanine residues incorporated into poly(β-benzyl L-aspartate) in the solid state (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 1983-1992 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C-nmr spectra of poly(β-benzyl L-aspartate) containing 13C-enriched [3-13C]L-alanine residues in the solid state were recorded by the cross polarization-magic angle spinning method, in order to elucidate the conformation-dependent 13C chemical shifts of L-alanine residues taking various conformations such as the antiparallel β-sheet, the right-handed α-helix, the left-handed α-helix, and the left-handed ω-helix forms obtained by appropriate treatment. The latter two conformations for L-alanine residues are achieved when L-alanine residues are incorporated into poly(β-benzyl L-aspartate). We found that the alanine Cβ carbon show significant 13C chemical shift displacement depending on conformational change, and gave the 13C chemical shift values at about 17 ppm for the left-handed ω-helix, 14 ppm for the left-handed α-helix, 15.5 ppm for the right-handed α-helix, and 21.0 ppm for the antiparallel β-sheet relative to tetramethylsilane.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360261202
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  • 7
    Electronic Resource
    Electronic Resource
    Salt-induced conformational change of random copolymers (Lys50Tyr50)n and (Lys50Phe50)n studied by 1H- and 13C-nuclear magnetic resonances. Aggregation behavior of helical segments (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 1065-1072 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H- and 13C-nmr studies of conformational transitions of random amino acid copolymers containing aromatic residues (Lys50Tyr50)n and (Lys50Phe50)n in the presence of neutral salts were performed to serve as models of the aggregation behavior of polypeptides of biological significance. The 1H and 13C signal intensities of Tyr and Phe residues decreased preferentially with increasing concentration of neutral salts such as NaCl and NaClO4. This behavior contrasts with that of (Lys)n in the presence of similar neutral salts, where the displacement of the 13C signal is clearly seen on transition from the random-coil to the helical conformation. On the basis of the previous conformational studies, the loss of the peak areas is ascribed to the presence of immobilized helical segments by hydrophobic interaction between aromatic side chains. The remaining resonances are due to the residual random-coil regions, since the values of nuclear Overhauser enhancements and chemical shifts are unchanged in the presence and absence of the neutral salts.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180504
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  • 8
    Electronic Resource
    Electronic Resource
    13C Nuclear magnetic resonance study of salt induced conformational change of basic polypeptides: Poly (L-lysine), poly (L-arginine), and poly (L-ornithine) (1978)
    New York : Wiley-Blackwell
    Biopolymers 17 (1978), S. 2587-2599 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A 13C-nmr study of the salt-induced helix-coil transition of the basic polypeptides poly(L-lysine) [(Lys)n], poly(L-arginine) [(Arg)n], and poly (L-ornithine) [(Orn)n] was performed to serve as a reference of the helical portion of histones and other proteins. As is the case with pH-induced helix-coil transition, the downfield displacement of the Cα and carbonyl carbon signals are observed in the helical state. The upfield shift of the Cβ signals, on the other hand, is noted in the salt-induced transition. Regardless of the differences in the side chains and also the salts used, very similar helix-induced chemical shifts are obtained for (Lys)n and (Arg)n. However, the displacement of the Cα, Cβ, and carbonyl carbons of (Orn)n in the presence of 4M NaClO4 is found to be almost 50% of that of (Lys)n and (Arg)n. This is explained by the fact that the maximum helical content is about 50%, consistent with the ORD result. Further, the motion of the backbone and side chains of the helical from was estimated by measuring the spin-lattice relaxation time (T1), nuclear Overhauser enhancement (NOE), and line width. In the case of (Lys)n, the motion of the side chains is charged very little in comparison with that of the random coil. Indicating that the aggregation of the salt-induced helix is small in contrast to that of the pH-induced helix. For (Arg)n, however, the precipitate of the helical polymers is mainly due to aggregation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1978.360171107
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  • 9
    Electronic Resource
    Electronic Resource
    A high-resolution 13C-nmr study of collagenlike polypeptides and collagen fibrils in solid state studied by the cross-polarization-magic angle-spinning method. Manifestation of conformation-dependent 13C chemical shifts and application to conformational characterization (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2279-2297 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have recorded high-resolution 13C-nmr spectra of collagen fibrils in the solid state by the cross-polarization-magic-angle-spinning(CP-MAS)method and analyzed the spectra with reference to those of collagenlike polypeptides. We used two kinds of model polypeptides to obtain reference 13C chemical shifts of major amino acid residues of collagen (Gly, Pro, Ala, and Hyp): the 31-helical polypeptides [(Gly)nII, (Pro)nII, (Hyp)n, and (Ala—Gly—Gly)nII], and the triple-helical polypeptides [(Pro—Gly—Pro)n and (Pro—Ala—Gly)n]. Examination of the 13C chemical shifts of these polypeptides, together with our previous data, showed that the 13C chemical shifts of individual amino acid residues are the same, within experimental error (±0.5 ppm), among different polypeptides with different primary sequences, if the conformations are the same. We found that the 13C chemical shifts of Ala residues of the 31-helical (Ala—Gly—Gly)n and triple-helical (Pro—Ala—Gly)n are significantly displaced, compared with those of the α-helix, β-sheet, and silk I form, and can be utilized as excellent probes to examine conformational features of collagen-like polypeptides. Further, the 13C chemical shifts of Gly and Pro residues in the triple-helical polypeptides are substantially displaced from those found in (Gly)nII and (Pro)nII of the 31-helix, reflecting further conformational change from the 31-helix to the supercoiled triple helix. In particular, the 13C chemical shifts of Gly C = O carbons of the triple-helical polypeptides are substantially displaced upfield (4.1-5.1 ppm), with respect to those of the 31-helical polypeptides. These displacements are interpreted by that Gly C = O of the former is not involved in NH … O = C hydrogen bonds, while this carbon of the latter is linked by these kinds of hydrogen bonds.On the basis of these 13C chemical shifts, as reference data for the collagenlike structure, we were able to assign the 13C-nmr peaks of Gly, Ala, Pro, and Hyp residues of collagen fibrils, which are in good agreement with the values expected from the model polypeptides mentioned above. We also discuss a plausible conformational change of collagen fibrils during denaturation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231111
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  • 10
    Electronic Resource
    Electronic Resource
    Cyclopolycondensation. XII. Polymerization mechanism of polybenzoxazinones in polyphosphoric acid mediumPresented in part at the 14th High Polymer Symposium, Kyoto, Japan, November 1965, and at the 16th High Polymer Symposium, Hakata, Japan, October 1967. A general review was given at the Gordon Research Conferences on Polymers, New London, N.H., U.S.A., July 1968. For Part XI of this series, see Hagiwara, Kurihara, and Yoda.1 (1969)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 7 (1969), S. 2897-2914 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization mechanism of polyphosphoric acid (PPA) solution polymerization of an aromatic diaminodicarboxylic acid with aromatic dicarboxylic acid derivatives was studied. By means of NMR methods, the initiation process for the polymerization of polybenzoxazinone in PPA medium was elucidated. The NMR spectra of a series of compounds were taken, and the salt formation of amino groups of monomer with PPA and the equilibrium between the salt and the free amino group were determined. It was established that the polymerization proceeded through the formation of phosphorylated intermediates to give the salt of amino groups of monomer with PPA. In the second step, the amine-PPA salt dissociates into the free amino group and PPA at the polymerization temperature above 140°C. Polymerization proceeds through the attack of “free” amino on phosphorylated carbonyl compounds to form polyamide acid of high molecular weight, and on subsequently being heated in PPA at higher temperatures, it undergoes an intramolecular cyclodehydration along the polymer chain to form polybenzoxazinones.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1969.150071013
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