Mononuclear copper(II) complexes of alloferons 1 and 2: a combined potentiometric and spectroscopic studies.
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.
Kowalik-Jankowska
Teresa
T
Faculty of Chemistry, University of Wrocław, Wrocław, Poland. terkow@wchuwr.chem.uni.wroc.pl
Biega
Łukasz
Ł
Kuczer
Mariola
M
Konopińska
Danuta
D
D003300:Copper / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D011199:Potentiometry; D013057:Spectrum Analysis
C510535:Alloferon; D009942:Organometallic Compounds; D010455:Peptides; D003300:Copper