Metal–DNA interactions

Metal ions can bind to DNA directly or indirectly through hydrogen bonding of the coordinating water molecules surrounding the metal ions. Metal binding to the bases usually disrupts base pair hydrogen bonding and destabilizes the double helix. Spectroscopic and X-ray data shows that the N7 atom of the purine or N3 of pyrimidine residues as well as exocyclic O atoms and the phosphate oxygen atoms are the preferential sites of metal binding. The binding of metals to DNA and RNA also influences indirectly the sugar conformation. As a result of this change in sugar puckering the two helical conformations of ADNA and B-DNA or RNA are characterized by the orientation of the bases with respect to the axis of the double helix. This may be the reason why some metal ions influence DNA synthesis and the replication process. In this paper we describe the influence of metal ion binding on the DNA structure and the variation of binding behaviour of different metal ions. q 2003 Elsevier Science B.V. All rights reserved.