A multi-approach study of the interaction of the Cu(II) and Ni(II) ions with alanylglycylhistamine, a mimicking pseudopeptide of the serum albumine N-terminal residue.
The protonation equilibria of alanylglycylhistamine (Ala-Gly-Ha) and the complexation of this ligand with Cu(II) and Ni(II) have been studied by pH-potentiometry, 1H and 14N NMR spectroscopy, electrospray ionization mass spectrometry (ESI-MS), circular dichroism (CD), UV-Vis spectrophotometry and electron paramagnetic resonance (EPR). From pH approximately 2-12, the following complexes: MLH, MLH(-1), MLH(-2) and MLH(-3) are successively formed in aqueous solutions, the ligand under its neutral form being noted L. At physiological pH, the MLH(-2) complex is predominant. The coordination in this complex is assumed by one amino, two deprotonated peptide and one imidazole nitrogen atoms. The ESI-MS study confirmed the formation of the MLH(-1), MLH(-2) and MLH(-3) complexes. The structure of MLH(-2) was determined by single crystal X-ray analysis. CD and UV-Vis techniques allowed us to propose that the imidazole-N3 nitrogen acts as the anchor group for the coordination to the metal(II) ions rather than the amino group. At high pH values, the further deprotonation of the N-H imidazole group, leading to the formation of MLH(-3), occurs, as revealed by 1H NMR spectroscopy.
Gizzi
P
P
Université Henri Poincaré--Nancy 1, UMR 7565 SRSMC CNRS-UHP, Groupe de Chimie Physique Organique et Colloïdale, BP 239, F-54506 Nancy-Vandoeuvre Cedex, France.
Henry
B
B
Rubini
P
P
Giroux
S
S
Wenger
E
E
D002942:Circular Dichroism / Q000379:methods; D003300:Copper / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray / Q000379:methods; D004151:Dipeptides / Q000737:chemistry* / Q000378:metabolism; D006632:Histamine / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D009532:Nickel / Q000737:chemistry* / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D011199:Potentiometry / Q000379:methods; D012709:Serum Albumin / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D013057:Spectrum Analysis / Q000379:methods
D004151:Dipeptides; D010455:Peptides; D012709:Serum Albumin; C502919:alanyl-glycyl-histamine; D003300:Copper; D009532:Nickel; D006632:Histamine