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Binding of Oxovanadium( IV ) to Tripeptides Containing Histidine and Cysteine Residues and Its Biological Implication in the Transport of Vanadium and Insulin‐Mimetic Compounds
Author(s) -
Garribba Eugenio,
Micera Giovanni,
LodygaChruscinska Elzbieta,
Sanna Daniele,
Sanna Gavino
Publication year - 2005
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200500304
Subject(s) - chemistry , electron paramagnetic resonance , deprotonation , amide , tripeptide , vanadium , ligand (biochemistry) , aqueous solution , coordination sphere , histidine , crystallography , inorganic chemistry , medicinal chemistry , stereochemistry , metal , ion , amino acid , organic chemistry , biochemistry , physics , receptor , nuclear magnetic resonance
The complexation of V IV O ion with three tripeptides of biological importance containing L ‐histidine or L ‐cysteine (HisGlyGly, GlyGlyHis and GlyGlyCys) has been studied. This study was performed in aqueous solution by the combined application of potentiometric and spectroscopic (electronic absorption and EPR) techniques. The results indicate that these oligopeptides, if a ligand‐to‐metal molar ratio of 10 or 15 is used, can keep V IV O ion in solution until the deprotonation of the amide group with the donor set (NH 2 , CO, N im ax ) for HisGlyGly or (COO – , CO) for GlyGlyHis and GlyGlyCys. In all the systems, at pH values around neutrality, a VOLH –2 species is formed with an (NH 2 , N – , N – , COO – ) donor set for HisGlyGly, (NH 2 , N – , N – , N im ) for GlyGlyHis and (NH 2 , N – ,N – , S – ) for GlyGlyCys. These species, and those with onedeprotonated amide group coordinated to the V IV O ion, can be detected by EPR spectroscopy. The N – (amide) contribution to the hyperfine coupling constant along the z axis, A z , depends on the total charge of the donor atoms in the equatorial plane. The participation of albumin in the transport of vanadium and insulin‐mimetic V IV O compounds is reconsidered based on these results. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)