Divalent cations are not required for the stability of the low-salt Z-DNA conformation in poly(dG-ethyl5dC).
It is demonstrated that poly(dG-ethyl5dC) adopts Z form in low-salt solution like poly(dG-methyl5dC). Its existence is, however, not contingent on the presence of divalent cations in the polynucleotide solution. The Z form is transformed into B form below room temperature. The arising B form cannot be transformed back into Z form by millimolar MgCl2 concentrations. On the contrary, the addition of MgCl2 at room temperature converts the low-salt Z form of poly(dG-ethyl5dC) into B form. It follows from the results that Z form is a stable DNA conformation not only at high but even at low ionic strengths.
Vorlicková
M
M
Institute of Biophysics, Czechoslovak Academy of Sciences, Brno.
Sági
J
J
D002413:Cations, Divalent; D055598:Chemical Phenomena; D002621:Chemistry; D002942:Circular Dichroism; D004247:DNA; D003853:Deoxyribonucleosides; D015636:Magnesium Chloride; D009690:Nucleic Acid Conformation; D011189:Potassium Chloride; D013057:Spectrum Analysis; D013696:Temperature
D002413:Cations, Divalent; D003853:Deoxyribonucleosides; D015636:Magnesium Chloride; C062463:poly(deoxyguanosyl-5-ethyldeoxycytidine); D011189:Potassium Chloride; D004247:DNA