Thermal transition of DNA measured by NMR spin‐echo technique

Abstract

Abstract The thermal helix–coil transition of DNA can be studied by means of the spin‐echo technique. The longitudinal spin–lattice relaxation time T 1 and the transvense spin–spin relaxation time T 2 of the DNA sample show a similar phase transition as observed spec‐trophotometrically with increasing and decreasing temperatures. Four slopes on the T 1 and T 2 temperature relationship curves were found and interpreted as functions of nonrelational hydration of the DNA molecule. The T 1 and T 2 values differ depending on the native or denatured state of the DNA molecule. The importance of the dynamic equilibrium between water molecules in the hydration lattice and steps in the denaturation of the DNA molecule are discussed. This phenomenon may be directly related to the nonrotational hydration.