New optical evidence of the cholesteric packing of DNA molecules in “re-entrant” phase

Yevdokimov, Yu. M.; Skuridin, S. G.; Salyanov, V. I.; Bobrov, Y.; Bucharsky, Vladislav A.; Kats, E. I.

doi:10.1016/j.cplett.2019.01.017

Cited by 5 publications

(4 citation statements)

References 38 publications

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“…It is possible if DAU molecules are intercalated between the nitrogen base pairs of ds DNA molecules in the content of the dispersion particles. Under these conditions the reactive groups of DAU (Figure 14b) are unavailable for chemical reactions [86].…”

Section: ~510 Nm)mentioning

confidence: 99%

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Liquid-Crystalline Dispersions of Double-Stranded DNA

et al. 2019

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In this review, we compare the circular dichroism (CD) spectra of liquid-crystalline dispersion (LCD) particles formed in PEG-containing aqueous-salt solutions with the purpose of determining the packing of ds DNA molecules in these particles. Depending on the osmotic pressure of the solution, the phase exclusion of ds DNA molecules at room temperature results in the formation of LCD particles with the cholesteric or the hexagonal packing of molecules. The heating of dispersion particles with the hexagonal packing of the ds DNA molecules results in a new phase transition, accompanied by an appearance of a new optically active phase of ds DNA molecules. Our results are rationalized by way of a concept of orientationally ordered “quasinematic” layers formed by ds DNA molecules, with a parallel alignment in the hexagonal structure. These layers can adopt a twisted configuration with a temperature increase; and as a result of this process, a new, helicoidal structure of dispersion particle is formed (termed as the “re-entrant” cholesteric phase). To prove the cholesteric pattern of ds DNA molecules in this phase, the “liquid-like” state of the dispersion particles was transformed into its “rigid” counterpart.

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Section: ~510 Nm)mentioning

confidence: 99%

“…The formation of cross-links between ds DNA molecules ordered in quasinematic layers of dispersion particle depends on the number of DAU molecules and on the number of copper atoms, as well as on the average distance between DNA molecules in the spatial structure of a dispersion particle [86].…”

Section: ~510 Nm)mentioning

confidence: 99%

Liquid-Crystalline Dispersions of Double-Stranded DNA

et al. 2019

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“…Появление аномальной полоcы в cпектpе КД ЖКД ДНК отражает, согласно теории [12,16], холестерическую упаковку соседних дц молекул ДНК в чаcтицаx ЖКД. Это означает, что при нагревании ЖКД, cфоpмиpованной в указанных условиях, гексагональная упаковка молекул ДНК меняется и происходит фазовый переход «гексагональная упаковка → «возвратная» холестерическая упаковка» молекул ДНК в частицах дисперсий [11].…”

Section: формирование частиц дисперсии «возвратной» холестерической фunclassified

“…Первый шаг в этом направлении был сделан в pаботе [10], в которой сопоставлены cпоcобы упаковки дц молекул ДНК в чаcтицаx ЖКД, cфоpмиpованныx в водно-солевых pаcтвоpах полиэтиленгликоля (ПЭГ) с разным осмотическим давлением. Кроме того, в работе [11] была обнаружена новая «возвратная» холестерическая фаза ДНК.…”

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Optical Properties of the DNA Particles of Cholesteric and «Re-Entrant» Cholesteric Phases

Yevdokimov¹,

Salyanov²,

Kompanets³

et al. 2019

Liq. Cryst. and their Appl.

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Phase exclusion of DNA molecules from polyethylene glycol (PEG) water-salt solutions leads to formation at room temperature of liquid-crystalline dispersions (LCD) with cholesteric and hexagonal packing of DNA molecules, determined by the osmotic pressure of the PEG solution. LCDs with cholesteric DNA packing (CLCD) have an intense negative band in the circular dichroism (CD) spectrum in the absorption region of nitrogen bases. LCD particles with hexagonal packing have no abnormal band. With increase of the solution temperature containing DNA CLCD particles, a decrease in the abnormal band in the CD spectrum is observed. Cooling of the dispersion leads not only to the restoration of the initial abnormal band, but also increases its amplitude. When the heating LCD with hexagonal DNA packing occurs, such band appears, i.e. there is the "hexagonal packing →"re-entrant"cholesteric packing phase transition. Cooling of the "re-entrant" cholesteric phase (C PEG = 240 mg ml-1) is accompanied by further increase in abnormal optical activity, whereas cooling of the dispersion formed at C PEG = 300 mg ml-1 causes decrease of the abnormal band amplitude. Consequently, equilibrium amplitude values of abnormal bands in CD spectra of these dispersion particles are realized as a result of multidirectional processes. When cooled to room temperature, the kinetic curves designating changes in the spatial structure of LCD particles with the "re-entrante" cholesteric packing of DNA molecules have a wave-like character. Comparison of these curves shows that the osmotic pressure increase of the PEG solution is accompanied by the increase of the wave-like character. Thus, the formation of the "re-entrant" cholesteric phases of DNA is determined not only by the osmotic pressure and temperature of PEG solution, but also by the average distance between DNA molecules in dispersion particles with the original hexagonal packing. Key words: liquid-crystalline ds DNA dispersion particles, circular dichroism, abnormal optical activity, cholesteric packing of ds DNA molecules, hexagonal packing of ds DNA molecules, temperature kinetics of formation of ds DNA cholesteric "re-entrant" phase, hexagonal → "re-entrant" phase of ds DNA transition.

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