Dresden 2009 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 18: Polyelectrolytes

CPP 18.7: Vortrag

Dienstag, 24. März 2009, 11:00–11:15, ZEU 114

DNA cholesteric phases: the role of DNA molecular chirality and DNA-DNA electrostatic interactions — •Andrey Cherstvy — IFF, Theorie-II, FZ Jülich, 52425 Jülich, Germany

DNA molecules form dense liquid crystalline twisted phases in vivo and in vitro. How the microscopic DNA chirality is transferred into intermolecular twist in these mesophases and what is the role of chiral DNA-DNA electrostatic interactions is still not completely clear. First, we give an extended overview of experimental observations on DNA cholesteric phases and discuss the factors affecting their stability. Then, we consider the effects of steric and electrostatic interactions of grooved charged helical molecules on the sign of cholesteric twist. We present some theoretical results on the strength of DNA-DNA chiral interactions, on DNA azimuthal correlations in cholesteric phases, on the micron-range pitch of DNA cholesteric phases, and on the regions of existence of DNA chiral phases stabilized by DNA-DNA electrostatic interactions [AC, JPCB, 112 12585 (2008)]. We suggest that 146 bp long DNA fragments with stronger affinities for nucleosome formation can form less chiral phases, with a larger left-handed cholesteric pitch. Also, the value of left-handed pitch formed in assemblies of homologous DNA fragments is predicted to be smaller than that of randomly sequenced DNAs. We expect also the cholesteric assemblies of several-kbp-long DNAs to require higher external osmotic pressures for their stability than the twisted phases of short nucleosomal DNA fragments at the same DNA lattice density.