Kowalik-Jankowska Teresa, Biega Łukasz, Kuczer Mariola, Konopińska Danuta
Faculty of Chemistry, University of Wrocław, Wrocław, Poland.
J Inorg Biochem. 2009 Jan;103(1):135-42. doi: 10.1016/j.jinorgbio.2008.09.013. Epub 2008 Oct 8.
Mononuclear copper(II) complexes of the alloferon 1 His-Gly-Val-Ser-Gly-His-Gly-Gln-His-Gly-Val-His-Gly, alloferon 2 Gly-Val-Ser-Gly-His-Gly-Gln-His-Gly-Val-His-Gly, Ac-alloferon 1 Ac-His-Gly-Val-Ser-Gly-His-Gly-Gln-His-Gly-Val-His-Gly and Ac-alloferon 2 Ac-Gly-Val-Ser-Gly-His-Gly-Gln-His-Gly-Val-His-Gly have been studied by potentiometric, UV-vis, CD and EPR spectroscopic methods. The potentiometric and spectroscopic data shows that acetylation of the amino terminal group induces significant changes in the coordination properties of the Ac-alloferons 1 and 2 compared to the alloferons 1 and 2, respectively. The presence of four (Ac-alloferon 1) or three (Ac-alloferon 2) histidyl residues provides a high possibility for the formation of macrochelates via the exclusive binding of imidazole-N donor atoms. The macrochelation suppresses, but cannot preclude the deprotonation and metal ion coordination of amide functions and the CuH(-3)L species with [N(Im), 3N(-)] bonding mode at pH above 8 are formed. The N-terminal amino group of the alloferons 1 and 2 takes part in the coordination of the metal ion and the 4N complex with [NH(2), 3N(Im)] coordination mode dominates at physiological pH 7.4 for alloferon 1 and the 3N [NH(2), CO, 2N(Im)] binding mode for alloferon 2. However, at higher pH values sequential amide nitrogens are deprotonated and coordinated to copper(II) ions.
已通过电位滴定法、紫外可见光谱法、圆二色光谱法和电子顺磁共振光谱法研究了别干扰素1（His-Gly-Val-Ser-Gly-His-Gly-Gln-His-Gly-Val-His-Gly）、别干扰素2（Gly-Val-Ser-Gly-His-Gly-Gln-His-Gly-Val-His-Gly）、乙酰化别干扰素1（Ac-His-Gly-Val-Ser-Gly-His-Gly-Gln-His-Gly-Val-His-Gly）和乙酰化别干扰素2（Ac-Gly-Val-Ser-Gly-His-Gly-Gln-His-Gly-Val-His-Gly）的单核铜（II）配合物。电位滴定和光谱数据表明，与别干扰素1和2相比，氨基末端基团的乙酰化分别导致乙酰化别干扰素1和2的配位性质发生显著变化。四个（乙酰化别干扰素1）或三个（乙酰化别干扰素2）组氨酸残基的存在为通过咪唑-N供体原子的专一性结合形成大环螯合物提供了很大可能性。大环螯合作用会抑制但不能排除酰胺官能团的去质子化和金属离子配位，并且在pH高于8时会形成具有[N(Im), 3N(-)]键合模式的CuH(-3)L物种。别干扰素1和2的N末端氨基参与金属离子的配位，在生理pH 7.4时，别干扰素1以[NH(2), 3N(Im)]配位模式为主导的4N配合物，别干扰素2以[NH(2), CO, 2N(Im)]结合模式为主导。然而，在较高pH值下，相继的酰胺氮会去质子化并与铜（II）离子配位。
