Coordination abilities of the 1-16 and 1-28 fragments of beta-amyloid peptide towards copper(II) ions: a combined potentiometric and spectroscopic study.
Stoichiometry, stability constants and solution structures of the copper(II) complexes of the (1-16H), (1-28H), (1-16M), (1-28M), (Ac-1-16H) and (Ac-1-16M) fragments of human (H) and mouse (M) beta-amyloid peptide were determined in aqueous solution in the pH range 2.5-10.5. The potentiometric and spectroscopic data (UV-Vis, CD, EPR) show that acetylation of the amino terminal group induces significant changes in the coordination properties of the (Ac-1-16H) and (Ac-1-16M) peptides compared to the (1-16H) and (1-16M) fragments, respectively. The (Ac-1-16H) peptide forms the 3N [N(Im)(6), N(Im)(13), N(Im)(14)] complex in a wide pH range (5-8), while for the (Ac-1-16M) fragment the 2N [N(Im)(6), N(Im)(14)] complex in the pH range 5-7 is suggested. At higher pH values sequential amide nitrogens are deprotonated and coordinated to copper(II) ions. The N-terminal amino group of the (1-16) and (1-28) fragments of human and mouse beta-amyloid peptide takes part in the coordination of the metal ion, although, at pH above 9 the complexes with the 4N [N(Im), 3N(-)] coordination mode are formed. The phenolate -OH group of the Tyr(10) residue of the human fragments does not coordinate to the metal ion.
Kowalik-Jankowska
Teresa
T
Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383 Wrocław, Poland. terkow@wchuwr.chem.uni.wroc.pl
Ruta
Monika
M
Wiśniewska
Kornelia
K
Lankiewicz
Leszek
L
D016229:Amyloid beta-Peptides / Q000737:chemistry* / Q000378:metabolism*; D000818:Animals; D003300:Copper / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007477:Ions / Q000378:metabolism; D051379:Mice; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism*; D011199:Potentiometry; D011485:Protein Binding; D011522:Protons; D013057:Spectrum Analysis; D013816:Thermodynamics
D016229:Amyloid beta-Peptides; D007477:Ions; D010446:Peptide Fragments; D011522:Protons; D003300:Copper