Schizophyllans carrying poly(N-substituted-acrylamidej-branches were synthesized from native schizophyllan through Ce(IV)-initiated radical homo- or co-polymerization of N-iso-propyl- and N-sec-butyl-acryl-amide. A series of structural analyses including elemental analysis, gel permeation chromatography, 1H NMR, and enzymatic degradation using β-1,3-glucanase revealed that schizophyllans (150 kDa) bearing long poly(N-substituted- acrylamide)-branches (ca. 290 kDa) are obtained. These SPG-conjugates form macromolecular complexes with certain homopolynucleotides such as poly(C), poly(dA), and poly(A) and then efficiently co-precipitate them on heating. For example, schizophyllan carrying poly(N-iso-propylacrylamide)-branches can selectively recover poly(C) from a mixture of poly(C) and poly(U) by simple heating (36°C) followed by centrifugation. HPLC analysis of the recovered polynucleotide revealed the high poly(C)-selectivity (poly(C):poly(U) = 95:5). Similarly, schizophyllan carrying more hydrophobic poly(N-iso-propylacrylamide- co-N-sec-butylacrylamide)-branches precipitates at lower temperature (ca. 20°C) and is applicable to isolation of poly(A) that forms less stable macromolecular complexes with SPG and SPG-derivatives (the dissociation temperatures are around 30°C).
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