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  • 11
    Electronic Resource
    Electronic Resource
    Conformation of poly(L-arginine). II. Complexes with polyanions (1978)
    New York : Wiley-Blackwell
    Biopolymers 17 (1978), S. 2783-2798 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformaitons of poly(L-arginine)/polyanion complexes were studies by CD measurements. The polyanions were the homoplolypeptides poly(L-glutamic acid) and poly(L-aspartic acid); the synthetic polyelectrolytes and polyethylenesulfonate; and the polynucleotides were native DNA, denatured DNA, and poly(U). It was found that poly(L-arginine) forms the α-helical conformation by interacting with the acidic homopolypeptides and the synthetic anionic polyelectrolytes. In each complex, poly(L-glutamic acid) is in the α-helical conformation, whereas poly(L-aspartic acid) is mostly in the random structure. The poly(L-glutamic acid) complex changed into the β-sheet structure at the transition temperature about 65°C in 0.01M cacodylate buffer (pH 7). Even in the presence of 5M urea, this complex remained in the α-helical conformation at room temperature. The existence of the stable complex of α-helical poly(L-arginine) and α-helical poly(L-glutamic acid) was successfully supported by the model building study of the complex. The α-helix of poly(L-arginine) induced by binding with polyacrylate was the most stable of the poly(L-arginine)-polyanion complexes examined as evidenced by thermal and urea effects. The lower helical content of the polyethylenesulfonate-complexed poly(L-aginine) was explained in terms of the higher charge density of the polyanion. On the other hand, native DNA, denatured DNA, and poly(U) were not effective in stabilizing the helical structure of poly(L-arginine). This may be due to the rigidity of polyanions and to the steric hindrance of bases. Furthermore, the distinitive structual behavior of poly(L-arginine) and poly(L-lysine) regarding polyanion interaction has been noticed throughout the study.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1978.360171204
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  • 12
    Electronic Resource
    Electronic Resource
    Conformation of poly(L-arginine). I. Effects of anions (1978)
    New York : Wiley-Blackwell
    Biopolymers 17 (1978), S. 2769-2782 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational transition of poly(L-agrignine) by binding with various mono-, di-, and polyvalent anions, especially with SO2-4, was studied by CD measurements. The intramolecular random coil-to-α-helix conformational transition and the subsequent transition to the β-turn-like structure was caused by binding with SO2-4. The binding data obtained from equilibrium dialysis experiments showed that the α-helical conformation of poly(L-arginine) is stabilized at a 1:3 stoichiometric ratio of bound SO2-4 to arginine residue; at higher free SO2-4 concentrations, the α-helix converts to the β-turn-like structure accompanied by a decrease in amount of bound SO2-4. The same conformaitonal transition of poly(L-arginine) also occurred in the solutions of other divalent anions (SO2-4, CO2-3, and HPO2-4) and polyvalent anions (P2O4-7, P3O5-10). Among the monovalent anions examined, CIO-4 and dodecyl sulfate were effective in including α-helical conformation, while the other monovalent anions (OH-, Cl-, F-, H2PO-4, HCO-3 and CIO-3) failed to induce poly(L-arginine) to assume the α-helical conformation. Thus, we noticed that, except for dodecyl sufate, the terahedral structure is common to the α-helix-forming anions. A well-defined model to the α-helical poly(L-arginine)/anion complex was proposed, in which both the binding stoichiometry of anions to the arginine residue and the tetrahedral structure of anions were taken into consideration. Based on these results, it was concluded that the tetrahedral-type anions stabilize the α-helical conformation of poly(L-arginine) by crosslinking between two guanidinium groups of nearby side chains on the same α-helix through the ringed structures stabilized by hydrogen bonds as well as by electrostatic interaction. Throughout the study it was noticed that the structural behavior of poly(L-arginine) toward anions is distinct from that of poly(L-lysine).
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1978.360171203
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  • 13
    Electronic Resource
    Electronic Resource
    Conformation of poly(L-homoarginine) (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1123-1135 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(L-arginine) assumes the α-helix in the presence of the tetrahedral-type anions or some polyanions by forming the “ringed-structure bridge” between guanidinium groups and anions which is stabilized by a pair of hydrogen bonds and electrostatic interaction [Ichimura, S., Mita, K. & Zama, M. (1978) Biopolymers 17, 2769-2782; Mita, K., Ichimura, S. & Zama, M. (1978) Biopolymers 17, 2783-2798]. This paper describes the parallel CD studies on the conformational effects on poly (L-homoarginine) of various mono-, di-, polyvalent anions and some polyanions, as well as alcohol and sodium dodecylsulfate. The random coil to α-helix transition of poly(L-homoarginine) occurred only in NaClO4 solution or in the presence of high content of ethanol or methanol. The divalent and polyvalent anions of the tetrahedral type (SO42-, HPO42-, and P2O74-), which are strong α-helix-forming agents for poly(L-arginine), failed to induce the α-helical conformation of poly(L-homoarginine). By complexing with poly(L-glutamic acid) or with polyacrylate, which is also a strong α-helix-forming agent for poly(L-arginine), poly(L-homoarginine) only partially formed the α-helical conformation. Monovalent anions (OH-, Cl-, F-, and H2PO4-) did not change poly(L-homoarginine) to the α-helix, and in the range of pH 2-11, the polypeptide remained in an unordered conformation. In sodium dodecylsulfate, poly(L-homoarginine) exhibited the remarkably enlarged CD spectrum of an extended conformation, while poly(L-arginine) forms the α-helix by interacting with the agent. Thus poly(L-homoarginine), compared with poly(L-arginine), has a much lower ability to form the α-helical conformation by interacting with anions. The stronger hydrophobicity of homoarginine residue in comparison with the arginine residue would provide unfavorable conditions to maintain the α-helical conformation.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190603
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  • 14
    Electronic Resource
    Electronic Resource
    Kinetics of chemical modification of arginine and lysine residues in calf thymus histone H1 (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1103-1112 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The arginine and lysine residues of calf thymus histone H1 were modified with large molar excesses of 2,3-butanedione and O-methylisourea, respectively. Kinetic study of the modification reaction of the arginine residue revealed that the reaction is divided into the two pseudo-first-order processes. About a third (1 Arg) of the total arginine residues of the H1 molecule was rapidly modified without causing any detectable structural change of the molecule, and the slow modification of the remaining arginine residues (2 Arg) led to a loss of the folded structure of H1. In the case of lysine residue modification, 93% (56 Lys) of the total lysine residues of the H1 was modified with the same rate constant, while 7% (4 Lys) of lysine residue remained unmodified. When the reaction was performed in the presence of 6M guanidine-HCl, all of lysine residues were modified. It is concluded that the 2 arginine and 4 lysine residues resistant to modification are buried in interior regions of the H1 molecule and play an important role in the formation of the H1 globular structure, while the other 1 arginine and 56 lysine residues are exposed to solvent.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200602
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