PMID- 30037061 OWN - NLM STAT- MEDLINE DCOM- 20181105 LR - 20181207 IS - 1420-3049 (Electronic) IS - 1420-3049 (Linking) VI - 23 IP - 7 DP - 2018 Jul 21 TI - Linking Temperature, Cation Concentration and Water Activity for the B to Z Conformational Transition in DNA. LID - 10.3390/molecules23071806 [doi] LID - 1806 AB - High concentrations of Na(+) or [Co(NH(3))(6)](3+) can induce the B to Z conformational transition in alternating (dC-dG) oligo and polynucleotides. The use of short DNA oligomers (dC-dG)(4) and (dm(5)C-dG)(4) as models can allow a thermodynamic characterization of the transition. Both form right handed double helical structures (B-DNA) in standard phosphate buffer with 115 mM Na(+) at 25 degrees C. However, at 2.0 M Na(+) or 200 muM [Co(NH(3))(6)](3+), (dm(5)C-dG)(4) assumes a left handed double helical structure (Z-DNA) while the unmethylated (dC-dG)(4) analogue remains right handed under those conditions. We have previously demonstrated that the enthalpy of the transition at 25 degrees C for either inducer can be determined using isothermal titration calorimetry (ITC). Here, ITC is used to investigate the linkages between temperature, water activity and DNA conformation. We found that the determined enthalpy for each titration varied linearly with temperature allowing determination of the heat capacity change (DeltaC(p)) between the initial and final states. As expected, the DeltaC(p) values were dependent upon the cation (i.e., Na(+) vs. [Co(NH(3))(6)](3+)) as well as the sequence of the DNA oligomer (i.e., methylated vs. unmethylated). Osmotic stress experiments were carried out to determine the gain or loss of water by the oligomer induced by the titration. The results are discussed in terms of solvent accessible surface areas, electrostatic interactions and the role of water. FAU - Ferreira, Jaime M AU - Ferreira JM AD - Estee Lauder Companies, Inc., Melville, NY 11747, USA. jferrier@estee.com. FAU - Sheardy, Richard D AU - Sheardy RD AD - Department of Chemistry and Biochemistry, Texas Woman's University, Denton, TX 76204, USA. rsheardy@twu.edu. LA - eng PT - Journal Article DEP - 20180721 PL - Switzerland TA - Molecules JT - Molecules (Basel, Switzerland) JID - 100964009 RN - 0 (Cations) RN - 059QF0KO0R (Water) RN - 9007-49-2 (DNA) SB - IM MH - Calorimetry MH - Cations/*chemistry MH - Circular Dichroism MH - DNA/*chemistry MH - *Nucleic Acid Conformation MH - *Temperature MH - Thermodynamics MH - Water/*chemistry PMC - PMC6099936 OTO - NOTNLM OT - B-DNA OT - Z-DNA OT - calorimetry OT - circular dichroism OT - conformational transitions OT - enthalpy OT - heat capacity COIS- The authors declare no conflict of interest. EDAT- 2018/07/25 06:00 MHDA- 2018/11/06 06:00 PMCR- 2018/07/21 CRDT- 2018/07/25 06:00 PHST- 2018/06/18 00:00 [received] PHST- 2018/07/18 00:00 [revised] PHST- 2018/07/19 00:00 [accepted] PHST- 2018/07/25 06:00 [entrez] PHST- 2018/07/25 06:00 [pubmed] PHST- 2018/11/06 06:00 [medline] PHST- 2018/07/21 00:00 [pmc-release] AID - molecules23071806 [pii] AID - molecules-23-01806 [pii] AID - 10.3390/molecules23071806 [doi] PST - epublish SO - Molecules. 2018 Jul 21;23(7):1806. doi: 10.3390/molecules23071806.