title: Spectroscopic investigation of cationic comb-type copolymers/DNA interaction: interpolyelectrolyte complex enhancement synchronized with DNA hybridization.
abstract: We have demonstrated that cationic comb-type copolymers consisting of a polycation backbone and abundant grafts of water-soluble polymers stabilize DNA hybrids. Furthermore, the copolymers were found to accelerate strand exchange reaction between a double-stranded DNA and its complementary single-stranded DNA. In this article, we investigated the effects of PLL-g-Dex on base pairs of a self-complementary DNA octamer, d(GGAATTCC). The soluble interpolyelectrolyte complex (IPEC) between the DNA and copolymer allowed us to characterize the complex by using spectroscopic methods under physiological ionic condition. Chemical shifts of nucleobase proton signals were not changed by PLL-g-Dex. Furthermore, the copolymer slightly changed the von't Hoff DeltaH accompanying the helix-coil transition of the octamer. These results indicated that the base pairs of the duplex DNA in the IPEC were not perturbed by the polycationic copolymer. It was obviously shown by temperature dependencies of proton and phosphorus NMR spectra that DNA/copolymer interaction was considerably enhanced in response to ds DNA formation. An increase in the density and total number of DNA negative charges upon hybrid formation likely caused the higher affinity of the copolymer with the ds form over that of the copolymer with the ss form. The IPEC formation of CCCs with DNA, however, seems highly sensitive to the coil-helix transition of the DNA.
authors.affiliation: Precursory Research for Embryonic Science and Technology (PRESTO) and Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Sato
authors.forename: Rui
authors.initials: R
authors.lastname: Moriyama
authors.forename: Sung Won
authors.initials: SW
authors.lastname: Choi
authors.forename: Arihiro
authors.initials: A
authors.lastname: Kano
authors.forename: Atsushi
authors.initials: A
authors.lastname: Maruyama
mesh_terms: D002412:Cations / Q000737:chemistry; D004277:DNA, Single-Stranded / Q000737:chemistry*; D003911:Dextrans / Q000737:chemistry*; D006358:Hot Temperature; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D011107:Polylysine / Q000737:chemistry*
chemical_list: D002412:Cations; D004277:DNA, Single-Stranded; D003911:Dextrans; D009838:Oligodeoxyribonucleotides; D011107:Polylysine