Lipophilicity of kinetically labile metal complexes through the example of antidiabetic Zn(II) and VO(IV) compounds.

The lipophilic character of several carrier ligands of antidiabetic Zn(II) and VO(IV) metal complexes were characterized by the traditional saturation shake flask method based on n-octanol/water partitioning. The transfer of the neutral ligand species to the organic phase was followed by UV spectrophotometry at various pH and the partition and distribution coefficients were calculated with the help of the proton dissociation constants and the spectra of the individual ligand species. Partition and distribution coefficients of the Zn(II) and VO(IV) complexes were determined by analysis of the metal ion content of the aqueous phases before and after separation by ICP-AES, their UV spectra and the corresponding concentration distribution curves.

Two pyridine derivatives as potential Cu(II) and Zn(II) chelators in therapy for Alzheimer's disease.

Two pyridine derivatives, DMAP and ENDIP, have been investigated as possible metal chelators in the therapy of Alzheimer's disease. Their complex formation with Cu(ii) and Zn(ii) were characterised in detail. In the case of ENDIP a high stability tetradentate ML complex is formed at physiological pH both with Cu(ii) and Zn(ii).

Biospeciation of various antidiabetic V(IV)O compounds in serum.

The interactions of various insulin mimetic oxovanadium(IV) compounds with serum proteins were studied in model systems and in ex vivo samples. For the modeling study, an earlier in situ method was extended and applied to the formation of ternary complexes of apotransferrin (apoTf)-V(IV)O-maltol (mal) and 1,2-dimethyl-3-hydroxy-4(1H)-pyridinone (dhp). Both systems were evaluated via simultaneous CD and EPR measurements.

Comparative studies on the biospeciation of antidiabetic VO(IV) and Zn(II) complexes.

The speciation of several insulin-mimetic/enhancing VO(IV) and Zn(II) complexes in human blood serum was studied and a comparison was made concerning the ability of the serum components to interact with the original metal complexes and the distribution of the metal ions between the low and the high molecular fractions of the serum. It was found that the low molecular mass components may play a larger role in transporting Zn(II) than in the case with VO(IV). Among the high molecular mass serum proteins, transferrin is the primary binder of VO(IV), and albumin is that of Zn(II).

Al(III)-binding ability of an octapeptide and its phosphorylated derivative.

A synthetic octapeptide, H-GlyGluGlyGluGlySerGlyGly-OH, and its phosphorylated Ser derivative were synthetized and their solution speciation and binding modes in their complexes with Al(III) were measured. One goal of the work was find a lead compound for the design of a selective peptide-based Al(III) chelator. pH-potentiometry was used to characterize the stoichiometry and the stability of the species formed in the interactions of the metal ion and the peptides, while multinuclear NMR was applied to characterize the binding sites of the metal ion in the complexes.

Solution structure of human beta-parvalbumin and structural comparison with its paralog alpha-parvalbumin and with their rat orthologs.

The aim of this research was to determine the structure of human beta-parvalbumin (109 amino acids) and to compare it with its paralog and ortholog proteins. The structure was determined in solution using multinuclear and multidimensional NMR methods and refined using substitution of the EF-hand Ca(2+) ion with a paramagnetic lanthanide. The resulting family of structures had a backbone rmsd of 0.