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Polysaccharide–polynucleotide complexes VIII. Cation‐induced complex formation between polyuridylic acid and schizophyllan
Author(s) -
Sakurai Kazuo,
Iguchi Ritsuko,
Koumoto Kazuya,
Kimura Taro,
Mizu Masami,
Hisaeda Yoshio,
Shinkai Seiji
Publication year - 2002
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.10189
Subject(s) - chemistry , polynucleotide , ligand (biochemistry) , circular dichroism , dimethyl sulfoxide , solvent , polysaccharide , stereochemistry , triple helix , organic chemistry , biochemistry , receptor
Schizophyllan belongs to the β‐1,3‐ D ‐glucan family, and dissolves as a single chain in dimethyl sulfoxide (DMSO) and as a triple helix in water, respectively. It is already known that when we prepare a mixture of poly(C) and schizophyllan in DMSO and subsequently exchange the solvent to water, poly(C) and schizophyllan can form a complex. When we applied this procedure to the poly(U) system, we could not induce the complex formation between poly(U) and schizophyllan at all. However, we found that addition of some alkaline cations is necessary to induce the complexation between poly(U) and schizophyllan. The complex stability strongly depends on both the cation species and the salt concentration. The complexation is sensitively reflected in the CD spectrum. The magnitude of the spectral change is followed by the order; Rb + ≫ K + > Na + ? Cs + . This cation order in the stability is confirmed by the fluorescence polarization measurements. 23 Na‐NMR spectroscopy reveals that the product system is stabilized by addition of the cations, suggesting that the OH group in schizophyllan and the phosphate anion in poly(U) synergistically form a specific ligand system for the cations. To the best of our knowledge, such a cation‐induced specific interaction between saccharides and polynucleotides has not been reported, and may provide a new clue to understand the biological role of β‐1,3‐ D ‐glucans. © 2002 Wiley Periodicals, Inc. Biopolymers 65: 1–9, 2002