Conformational flexibility of poly (dG-m5dC) under very low salt conditions

Summary The methylated DNA polymer poly (dG-m⁵dC) which exhibits a B helical conformation in solutions containing 20 mM NaCl, undergoes a gradual and reversible transition to the Z conformation as the NaCl concentration is lowered. The midpoint of this transition occurs around 5–6 mM NaCl. The conformational flexibility of this polymer at such low NaCl concentrations opens up the possibility of studying the effects of other perturbants with negligible interference from salt concentration effects.