Temperature dependent Z→B transitions in poly (dG-dC)

Abstract

The effect of temperature on the Z-form of poly(dG-dC) in a medium of low dielectric constant has been studied. A novel temperature-dependent reversible Z⇌B transition is observed in 60% (v/v) alcohol. The mid-point transition(T₁ is found to be lowered from 65°C to 40°C when an extra 1.5m M NaCl was added to the solution having a sodium:phosphate ratio of 1:1. Analysis of the temperature dependent Z-B transitions both in the presence and absence of 1.5 mM NaCl reveals a positive change in enthalphy.