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Pure Appl. Chem. 76(2), 375-388, 2004

Adenosine 5'-triphosphate (ATP^4-): Aspects of the coordination chemistry of a multitalented biological substrate

H. Sigel

Department of Chemistry, Inorganic Chemistry, University of Basel, Spitalstrasse 51, CH-4056 Basel, Switzerland

Abstract: Firstly, the self-stacking properties of ATP^4- and the effects of metal ions and protons on these properties are described. Some examples involving macrochelate formation between phosphate-coordinated metal ions (M²+;) and N7 of the adenine residue in MATP^2- are discussed, and this is followed by considerations on mixed ligand complexes consisting of ATP^4-, M^2+, and amino acid anions with side chains that allow either aromatic-ring stacking or hydrophobic interactions with the adenine moiety; this gives rise to selectivity. Next, the properties of diphosphorylated 9-[2-(phosphonomethoxy)ethyl]adenine (PMEA^2-; Adefovir), i.e., of PMEApp^4-, are compared with those of (2'-deoxy)ATP^4- with regard to their metal ion-binding qualities, and in this way it can be explained why PMEApp^2- is initially an excellent substrate for nucleic acid polymerases. Of course, after incorporation of the PMEA residue into the growing nucleic acid chain, this is terminated and this is how PMEA exerts its antiviral properties [its bis(pivaloyloxymethyl)ester, Adefovir dipivoxil, was recently approved for use in hepatitis B therapy]. Finally, the change in free energy connected with (macro)chelate formation or intramolecular stacking interactions and the effect of a reduced dielectric constant of the solvent on the stability of complexes and their structures in solution is considered.

*Plenary lecture presented at the 2nd Santa Mar�a Workshop on Chemistry Devoted to Bioinorganic Chemistry, Santa Mar�a del Mar, Havana, Cuba, 7-11 July 2003. Other presentations are published in this issue, pp. 321-388.

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