Supramolecular interaction of inositol phosphates with Cu(ii): comparative study of InsP6–InsP3

Abstract

myo-inositol phosphates are an important group of biomolecules that are present in all eukaryotic cells. The most abundant member of this family in nature is InsP₆ (H₁₂L¹), which interacts strongly with inorganic and organic cations. This interaction is essential for determining the possible functions of this biomolecule. A few crystal structures containing InsP₆, and a divalent cation, have been reported showing a great versatility of this bioligand. Ins(1,2,3)P₃ (H₆L²) is another important member of the group, usually thought as a safe cellular iron ligand. No crystal structures showing the interaction of L² with metal ions can be found in the literature. In this work we characterized by X-ray diffraction two polynuclear complexes, [Cu₃(H₆L¹)(phen)₅] (phen = 1,10-phenanthroline) (1) and [Cu₂(H₂L²)(H₂O)(terpy)₂] (terpy = 2,2′:6′,2′′-terpyridine) (2). The crystal structure of 2 furnishes, for the first time, a picture of the coordination ability of Ins(1,2,3)P₃ against a divalent metal ion. In addition, a PDB survey was performed on all InsPs to frame the coordination modes derived from our small-molecule supramolecular approach within a more realistic biological context.