Molecular weight control of curdlan (β-1,3-glucan polysaccharide) provides unique polynucleotide binding properties

Abstract

Recently, we found that schizophyllan belonging to a β-1,3-glucan polysaccharide family forms macromolecular complexes with certain single-stranded polynucleotides. The specific complex formation is originated from the β-1,3-glucan skeleton in the main chain. In this paper, we have reported that curdlan, which is a β-1,3-glucan polysaccharide without a side chain glucose unit, shows unique poly(C) binding properties different from those of schizophyllan; in the experiments using curdlan samples with the controlled molecular weight, the complexation ability appeared only in a limited "Mw range window". Stoichiometric analysis revealed that the "Mw range window" appears as a result of the competition between curdlan-curdlan self-association and curdlan-polynucleotide complexation. Furthermore, when the experiments were extended to other polynucleotides such as poly(A), poly(dA) and poly(dT), the "Mw range window" also appeared at their characteristic molecular weights. We believe, therefore, that curdlan can be applicable, in spite of its cheapness, as a precious functional material to gene technology.