Pressure-induced helix–coil transition of DNA copolymers is linked to water activity |
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Authors: | Gamal Rayan Robert B. Macgregor Jr. |
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Affiliation: | aLeslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario, Canada M5S 3M2 |
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Abstract: | We have investigated the effect of reduced water activity on the pressure-stability of double-stranded DNA polymers, poly[d(A-T)] and poly[d(I-C)]. Water activity was modulated by the addition of ethylene glycol and glycerol. The ionic strength of the medium was such that pressure had a destabilising effect on the polymers in the absence of cosolvents. The molar volume change of the heat-induced helix to coil transition (ΔVT) becomes more positive as the activity of water was reduced, suggesting that the pressure-induced denaturation of DNA polymers would not occur at very low water activity. This would imply that water plays a crucial role in the pressure denaturation of DNA, much like that in pressure denaturation of proteins where the driving force of the process is the penetration of water molecules into the protein core [Hummer et al., Proc Natl Acad Sci USA 1998, 95, 1552–1555]. |
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Keywords: | DNA Helix to coil transition Volume change Expansivity change Pressure denaturation Water activity |
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