Hofmeister series and ionic effects of alkali metal ions on DNA conformation transition in normal and less polarised water solvent |
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Authors: | Jing Wen Xin Shen Hao Shen |
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Institution: | 1. The Key Laboratory of Beam Technology and Material Modification of the Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing, China;2. Beijing Radiation Center, Beijing, China |
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Abstract: | Normal and less polarised water models are used as the solvent to investigate Hofmeister effects and alkali metal ionic effects on dodecamer d(CGCGAATTCGCG) B-DNA with atomic dynamics simulations. As normal water solvent is replaced by less polarised water, the Hofmeister series of alkali metal ions is changed from Li+ > Na+ ? K+ ? Cs+ ? Rb+ to Li+ > Na+ > K+ > Rb+ > Cs+. In less polarised water, DNA experiences the B→A conformational transition for the lighter alkali metal counterions (Li+, Na+ and K+). However, it keeps B form for the heavier ions (Rb+ and Cs+). We find that the underlying cause of the conformation transition for these alkali metal ions except K+ is the competition between water molecules and counterions coupling to the free oxygen atoms of the phosphate groups. For K+ ions, the ‘economics’ of phosphate hydration and ‘spine of hydration’ are both concerned with the DNA helixes changing. |
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Keywords: | Hofmeister effect ionic effects molecular liquids less polarised solvent DNA |
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