Nucleic acid zinc complexes

Metal ions can enhance the resolution of nucleic acids and amino acids in MECC. Zinc perchlorate (0-30 mM) has been found useful as a complexing reagent for histidine-containing peptides. 

Zinc finger proteins have recently been classified into eight distinct structural groups distinguished by their tertiary structural folds around the zinc coordination complex and the spatial arrangement of secondary structural elements that contribute zinc ligands. Table 1 lists representative members from each of six of these eight stmctural classes that are known to interact directly with nucleic acids. These are discussed in turn. 

A novel class of nucleic acid mimics has been described which possess two ethylenediamine moieties for intermolecular metal co-ordination (25). In the presence of Zn + ions and template DNA, the analogues (25) form relatively stable structures, stabilised by the co-ordination of adjacent chelating moieties with zinc ions. It was shown that with an oligothymidine template and the adenine derivative of (25) that a 2 1 complex was formed, which showed a biphasic melting transition. Short RNA duplexes (3-4 bp) are considerably stabilised if both termini of the duplexes are bridged by non-nucleotidic linkers. For example, the pairing of rGAA with rUUC in such a cyclic system exhibits a Tm of 36°C in IM salt solution. 

An interesting metal-binding motif in proteins is the zinc finger, which contains a / ribbon-turn-a helix motif that binds a zinc ion via four sulfur atoms of cysteine residues, or via two such sulfur atoms and two nitrogen atoms (from histidine). This motif, first identified by NMR studies, has been found in the crystal structures of several protein-nucleic acid complexes. ... 

He Y, Imhoff R, Sahu A et al (2009) Solution stmcture of a novel zinc finger motif in the SAP30 polypeptide of the Sin3 corepressor complex and its potential role in nucleic acid recognition. Nucleic Acids Res 37 2142-2152... 

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