Polynucleotide conformation, metal

Metal Binding Can Induce Conformational Changes of Polynucleotide Structures 24... 

METAL BINDING CAN INDUCE CONFORMATIONAL CHANGES OF POLYNUCLEOTIDE STRUCTURES... 

An interaction of metal ions with phosphates usually leads to stabilization of polynucleotide secondary and tertiary stmctures, depending on the metal ions and their concentrations, whereas base binding or chelating base and phosphate by the same metal ion may result in destabilization, conformational change, or denaturation of the polynucleotide structures (see also Sections 3.3.1 and 3.3.2). However, phosphate-specific binding can also induce significant conformational changes in DNA structure. The mechanisms of the latter structural interconversions are... 

Metal Ions can produce a large variety of other effects on nucleic acids that could be deleterious if they occur during genetic information transfer. Metal ions can bring about the degradation of RNA (17, 18, 19), changes in the specificity of enzymes that act on DNA (20), changes in the conformation of polynucleotides and nucleic acid - protein complexes (21). 

The ability of metal complexes to form more than one bond to the polynucleotide, especially in Form HI, results in various forms of cross link between the complementary strands of the helix. The coordination number, geometry, and types of ligand all dictate a remarkable range of conformational changes and interactions with DNA, including base pair specificity. 

Scope of data. This chapter covers metal ion interactions with DNA, RNA and polynucleotides. A few related data involving oligonucleotides are included when necessary and appropriate. Oligomers when crystallized for X-ray analysis resemble polymers and are treated as such. The subject matter is limited to direct effects of metal binding, e.g. metal association constants and binding characteristics, metal binding effects on conformation, and metal-catalyzed depolymerization. There are of course many other phenomena that could be included, but are deemed unsuitable for tabulation. The effects of metal binding to DNA and RNA that involve interaction with proteins are covered only when the primary effect is on the nucleic acid moiety. 

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