Interaction of Al(III) with the peptides AspAsp and AspAspAsp.
The interactions of Al(III) with the dipeptide AspAsp and the tripeptide AspAspAsp in aqueous solutions were studied by pH-potentiometry and multinuclear 1H- and 13C- nuclear magnetic resonance (NMR) spectroscopy. Their numerous negatively charged COO(-) functions allow these ligands to bind Al(III) even in weakly acidic solutions. Various mononuclear 1:1 complexes are formed in different protonation states. 13C-NMR spectroscopy unambiguously proved participation of the COO(-) functions in a monodentate or chelating mode in Al(III) binding, however, the terminal-NH(2) group seems to be excluded from the coordination. Depending on the metal ion to ligand ratio precipitation occurs at pH approximately 5 to 6. This indicates that the COO(-) groups at the low level of preorganization in such small peptides are not sufficient to keep the Al(III) ion in solution and to prevent the precipitation of Al(OH)(3) at physiological pH. To achieve this, a more specific arrangement of the side-chain donors seems necessary.
Kilyén
Melinda
M
Biocoordination Chemistry Research Group of the Hungarian Academy of Sciences, University of Szeged, PO Box 440, Szeged, Hungary.
Forgó
Péter
P
Lakatos
Andrea
A
Dombi
György
G
Kiss
Tamás
T
Kotsakis
Nikos
N
Salifoglou
Athanassios
A
D000535:Aluminum / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D004151:Dipeptides / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008024:Ligands; D019906:Nuclear Magnetic Resonance, Biomolecular; D009842:Oligopeptides / Q000737:chemistry*; D011522:Protons
D002412:Cations; D004151:Dipeptides; D008024:Ligands; D009842:Oligopeptides; D011522:Protons; C108952:aspartyl-aspartic acid; D000535:Aluminum