Polysaccharide-polynucleotide complexes (15): Thermal stability of schizophyllan (SPG)/poly(C) triple strands is controllable by α-amino acid modification

Munenori Numata, Takahiro Matsumoto, Mariko Umeda, Kazuya Koumoto, Kazuo Sakurai, Seiji Shinkai

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22 Citations (Scopus)


Schizophyllan (SPG), a β-1,3-glucan polysaccharide which is known to form macromolecular complexes with certain polynucleotides, was modified by a reductive amination method with α-amino acids (Arg, Lys, and Ser). The thermal stability of the complexes as estimated by Tm was enhanced in SPG-Arg and SPG-Lys conjugates which have pI values higher than the pH of the medium (8.0). The Tm shift increased with the increase in the percentage of α-amino acid introduced and the highest Tm values attained were 64°C for SPG-Arg conjugate and 62°C for SPG-Lys conjugate, which are higher by 13 and 11°C, respectively, than those of the unmodified SPG+poly(C) complex. In the SPG-Ser conjugate with a pI lower than the medium pH (8.0), the Tm values decreased with an increase in the percentage of Ser. Formation of the macromolecular complex was no longer detected above 13.2% Ser. The findings indicate that the Tm values are easily controllable by the type and percentage of the introduced α-amino acids. We believe, therefore, that the present conjugates, consisting of naturally originated SPG and α-amino acids, provide an important lead for developing nontoxic artificial vectors and to control the affinity with polynucleotides in response to medium pH and temperature.

Original languageEnglish
Pages (from-to)163-171
Number of pages9
JournalBioorganic Chemistry
Issue number2
Publication statusPublished - Apr 2003

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Drug Discovery
  • Organic Chemistry


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