Molecular mechanisms for the B-Z transition in the example of poly[d(G-C)•d(G-C)] polymers.: A critical review

Despite the dense literature about the biological role of the left-handed Z-DNA, the molecular mechanisms, which drive the B-Z transition, have remained obscured and contrasting results have appeared in the literature on this subject. As a result, the chemical-biological community has constantly ignored the analysis of the molecular mechanisms leading to Z-DNA. This review covers the molecular mechanisms for the B-Z transition as proposed in the last 30 years and the consequent progression of ideas. It is shown that the formation of a nucleation site in the DNA and its energy-cost appear as common characteristics from various models and lead to the useful concept of cooperativity and to postulate the existence of a salt threshold capable to transform contrasting results into complementary.