Kowalik-Jankowska Teresa, Ruta Monika, Wiśniewska Kornelia, Lankiewicz Leszek
Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383 Wrocław, Poland.
J Inorg Biochem. 2003 Jul 1;95(4):270-82. doi: 10.1016/s0162-0134(03)00128-4.
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.
测定了人（H）和小鼠（M）β-淀粉样肽的（1-16H）、（1-28H）、（1-16M）、（1-28M）、（Ac-1-16H）和（Ac-1-16M）片段与铜（II）配合物在pH值为2.5 - 10.5的水溶液中的化学计量比、稳定常数和溶液结构。电位滴定和光谱数据（紫外可见光谱、圆二色光谱、电子顺磁共振光谱）表明，与（1-16H）和（1-16M）片段相比，氨基末端基团的乙酰化分别导致（Ac-1-16H）和（Ac-1-16M）肽的配位性质发生显著变化。（Ac-1-16H）肽在较宽的pH范围（5 - 8）内形成3N [N(Im)(6)，N(Im)(13)，N(Im)(14)]配合物，而对于（Ac-1-16M）片段，推测在pH范围5 - 7内形成2N [N(Im)(6)，N(Im)(14)]配合物。在较高pH值下，连续的酰胺氮去质子化并与铜（II）离子配位。人和小鼠β-淀粉样肽的（1-16）和（1-28）片段中的N末端氨基参与金属离子的配位，尽管在pH高于9时会形成具有4N [N(Im)，3N(-)]配位模式的配合物。人片段中Tyr(10)残基的酚羟基不与金属离子配位。
