2007 Volume 56 Issue 6 Pages 428-432
Individual giant DNA chains show a discrete conformational change, the folding phase transition, between an elongated coil state and a folded compact state under existence of multivalent cations, polymer chains, multivalent anions, and alcohols on the level of a single molecular chain. The stiffness of a polymer chain is essential for the transition. The single DNA chain also expresses a rhythmic conformational change between the coil and folded states under a thermodynamically open condition such as a local temperature gradient generated by optical tweezers. The coupling between the folding phase transition and the thermodynamically open condition is essential. These will be common for semiflexible polymer chains.
