Spontaneous formation of liquid crystalline phases and phase transitions in highly concentrated plasmid DNA
Journal article, 2011
The liquid crystalline (LC) properties of two supercoiled plasmid DNA samples, pBSK (2958 bp) and pGEM (3000 bp), have been studied using polarised light microscopy (PLM), circular dichroism (CD) and UV-Vis spectroscopy. The influence of methods of isolation on plasmid LC behaviour is described, and using PLM we have demonstrated the spontaneous formation of cholesteric fingerprint-like textures. Preliminary studies of LC phase transitions in pGEM show the irreversibility of LC phase formation, as a consequence of changes in the tertiary structure of supercoiled plasmids. Using UV-Vis spectroscopy a hyperchromic effect was observed with increasing temperature. The CD spectra clearly showed structural changes, and probably mismatching of DNA bases, during cooling. Finally, we have observed an irreversible phase transition in plasmid DNA which is very different from that previously reported in linear DNA.
nucleic acids
fingerprint-like texture
supercoiled dna
cholesteric phase
shock
plasmid DNA
hyperchromic effect
supercoiling
thermal-denaturation
phase transition
DNA
circular dichroism
escherichia-coli
growth temperature
microscopy
bacteria
liquid crystal
linking
dimensions
isolation techniques
Author
Piotr Hanczyc
Chalmers, Chemical and Biological Engineering, Physical Chemistry
K. Matczyszyn
Wrocław University of Science and Technology
K. Pawlik
AKademia Medyczna Wroclawiu
Polish Academy of Sciences
J. Olesiak
Wrocław University of Science and Technology
H. Leh
Laboratoire de Biologie et de Pharmacologie Appliquee
M. Buckle
Laboratoire de Biologie et de Pharmacologie Appliquee
Liquid Crystals
0267-8292 (ISSN) 1366-5855 (eISSN)
Vol. 38 4 461-468Subject Categories
Chemical Sciences
DOI
10.1080/02678292.2011.552740