Liquid crystalline phase behavior of high molecular weight DNA: a comparative study of the influence of metal ions of different size, charge and binding mode.
The ability of Li(+), Na(+), K(+), Rb(+), Cs(+), Mg(2+), Ca(2+), Sr(2+), Ba(2+), Cu(2+), Cd(2+), Al(3+), V(4+), Hg(2+), Pd(2+), Au(3+), and Pt(4+) to provoke liquid crystalline (LC) phases in high molecular weight DNA was investigated. The alkali and alkaline earth metal ions provoked typical cholesteric/columnar structures, whereas transition metal ions precipitated DNA into solid/translucent gel-like aggregates. Heavy metal ions reduced viscosity of DNA solution, disrupting rigid, rod-like DNA structure necessary for LC textures. Three-layer quantum mechanical-molecular mechanical (QM/MM) studies of Li(+), Na(+), K(+), Mg(2+), and Ca(2+) binding DNA fragment suggested several possible binding modes of these ions to the phosphate groups. The dianion mode of metal binding, involving the phosphate groups of both strands of DNA, allowed for higher DNA binding affinity of the alkaline earth metal ions. These results have implications in understanding the biological role of metal ions and developing DNA-based sensors and nanoelectronic devices.
Chemical Sciences and Technology Division and Computational Modeling and Simulation Section, National Institute for Interdisciplinary Science and Technology, Council of Scientific and Industrial Research, Thiruvananthapuram, India.
Neethu
N
Sundaresan
Cherumuttathu H
CH
Suresh
Thresia
T
Thomas
T J
TJ
Thomas
C K S
CK
Pillai
D001665:Binding Sites; D002412:Cations; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D050866:Liquid Crystals; D008670:Metals / Q000737:chemistry / Q000378:metabolism*; D008970:Molecular Weight; D009690:Nucleic Acid Conformation; D044367:Phase Transition; D014783:Viscosity
D002412:Cations; D008670:Metals; D004247:DNA