Abstract
The left-handed helical conformation of various polynucleotides has been seen in solution at higher salt concentration than has the right-handed helical conformation of the corresponding polymer. However, studies of conformational transitions in the mixed polymer poly(rG-dC).cntdot.poly(rG-dC) showed that this polynucleotide appears to exist in a Z conformation under low-salt conditions, converts to an A helix at intermediate salt, and reverts to a left-handed helix at high-salt concentration.