Liquid-crystal microphases of low-molecular weight double stranded nucleic acids and synthetic polynucleotides

• Published in: Polymer science USSR 1984, Vol.26 (11), p.2730-2740
• Main Authors: Yevdokimov, Yu.M, Skuridin, S.G, Akimenko, N.M
• Format: Article
• Language: English
• ISSN: 0032-3950; 1878-268X
• DOI: 10.1016/0032-3950(84)90233-8

A study has been made of the properties of microphases formed as a result of phase separation occurring during the mixing of water-salt solutions of native double-stranded DNA, and of synthetic double-stranded polynucleotides, with water-salt solutions of polyethylene glycol. At a definite concentration of polyethylene glycol it was found that molecules of low-molecular weight DNAs or of synthetic polynucleotides, may be in the liquid-crystal state. An intense ( Δϵ 270 ∼ 100 units) band in the circular dichroism spectrum accompanying the appearance of liquid-crystal microphase points to the existence of long-range helical order in the arrangement of nitrous bases in the composition of DNA molecules or of polynucleotides forming liquid-crystal microphases. It is shown that, irrespective of the direction of twist of polynucleotide double helices are two groups of liquid-crystal microphases differing as to the sign of intense bands in the circular dichroism spectra: liquid-crystal microphases belonging to the first group are characterized by an intense negative band, compared with an intense positive band of those belonging to the second group.