Abundant graft chains do not influence coil-to-helix but α-to-β transition of polylysine backbone, resulting in thermoreversible β-to-α transition

Rui Moriyama, Sung Won Choi, Naohiko Shimada, Arihiro Kano, Atsushi Maruyama

Research output: Contribution to journalArticle

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Abstract

We have demonstrated that cationic comb-type copolymers (PLL-g-Dex) consisting of a cationic polylysine backbone and abundant grafts of water-soluble polymers stabilize DNA hybrids. Furthermore, the copolymers were found to accelerate the strand exchange reaction between a double-stranded DNA and its complementary single-stranded DNA. In this study, we investigated pH-induced coil-to-helix and temperature-induced α-to-β transition of PLL-g-Dex to evaluate the effect of the graft chains on conformation of the polylysine backbone. The coil-to-helix transition was hardly influenced by the grafted dextran. The copolymer having 24 mol% (93 wt%) dextran still underwent coil-to-helix transition. No change in transition pH with dextran grafting density of the copolymer was observed. In contrast to the coil-to-helix transition, the dextran grafts impacted the temperature-induced α-to-β transition. The graft chains even at 1 mol% (38 wt%) affected α-to-β transition of the PLL backbone. The transition temperature increased from 45°C to 77 °C by 11 mol% (88 wt%) dextran grafting, resulted in stabilization of helical structure at the higher temperature. Furthermore, thermoreversible β-to-α transition of the copolymer was observed for the copolymer with a particular grafting degree. The grafted dextran seemingly modified inter-strands or inter-segments interactions of the polylysine backbones which are required for β-sheet assembling.

Original languageEnglish
Pages (from-to)1381-1387
Number of pages7
JournalReactive and Functional Polymers
Volume67
Issue number11 SPEC. ISS.
DOIs
Publication statusPublished - Jan 1 2007

Fingerprint

Polylysine
Dextran
Dextrans
Grafts
Copolymers
Transplants
DNA
Phase locked loops
temperature
Temperature
stabilization
polymer
Comb and Wattles
Transition Temperature
Single-Stranded DNA
Superconducting transition temperature
Conformations
Polymers
Stabilization
Complementary DNA

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Environmental Chemistry
  • Biochemistry
  • Chemical Engineering(all)
  • Polymers and Plastics
  • Materials Chemistry

Cite this

Abundant graft chains do not influence coil-to-helix but α-to-β transition of polylysine backbone, resulting in thermoreversible β-to-α transition. / Moriyama, Rui; Choi, Sung Won; Shimada, Naohiko; Kano, Arihiro; Maruyama, Atsushi.

In: Reactive and Functional Polymers, Vol. 67, No. 11 SPEC. ISS., 01.01.2007, p. 1381-1387.

Research output: Contribution to journalArticle

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abstract = "We have demonstrated that cationic comb-type copolymers (PLL-g-Dex) consisting of a cationic polylysine backbone and abundant grafts of water-soluble polymers stabilize DNA hybrids. Furthermore, the copolymers were found to accelerate the strand exchange reaction between a double-stranded DNA and its complementary single-stranded DNA. In this study, we investigated pH-induced coil-to-helix and temperature-induced α-to-β transition of PLL-g-Dex to evaluate the effect of the graft chains on conformation of the polylysine backbone. The coil-to-helix transition was hardly influenced by the grafted dextran. The copolymer having 24 mol{\%} (93 wt{\%}) dextran still underwent coil-to-helix transition. No change in transition pH with dextran grafting density of the copolymer was observed. In contrast to the coil-to-helix transition, the dextran grafts impacted the temperature-induced α-to-β transition. The graft chains even at 1 mol{\%} (38 wt{\%}) affected α-to-β transition of the PLL backbone. The transition temperature increased from 45°C to 77 °C by 11 mol{\%} (88 wt{\%}) dextran grafting, resulted in stabilization of helical structure at the higher temperature. Furthermore, thermoreversible β-to-α transition of the copolymer was observed for the copolymer with a particular grafting degree. The grafted dextran seemingly modified inter-strands or inter-segments interactions of the polylysine backbones which are required for β-sheet assembling.",
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