Interaction of Cu(II) and Ni(II) with the 63-93 fragment of histone H2B.
Chromatin proteins are believed to represent reactive sites for metal ion binding. We have synthesized the 31 amino acid peptide Ac-NSFVNDIFERIAGEASRLAHYNKRSTITSRE-NH2, corresponding to the 63-93 fragment of the histone H2B and studied its interaction with Cu(II) and Ni(II). Potentiometric and spectroscopic studies (UV-vis, CD, NMR and EPR) showed that histidine 21 acts as an anchoring binding site for the metal ion. Complexation of the studied peptide with Cu(II) starts at pH 4 with the formation of the monodentate species CuH2L. At physiological pH values, the 3N complex (N(Im), 2N(-)), CuL is favoured while at basic pH values the 4N (N(Im), 3N(-)) coordination mode is preferred. Ni(II) forms several complexes with the peptide starting from the distorted octahedral NiH2L at about neutral pH, to a square planar complex where the peptide is bound through a (N(Im), 3N(-)) mode in an equatorial plane at basic pH values. These results could be important in revealing more information about the mechanism of metal induced toxicity and carcinogenesis.
Zavitsanos
Kimon
K
Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece.
Nunes
Ana Mónica P C
AM
Malandrinos
Gerasimos
G
Kállay
Csilla
C
Sóvágó
Imre
I
Magafa
Vassiliki
V
Cordopatis
Paul
P
Hadjiliadis
Nick
N
D000595:Amino Acid Sequence; D001665:Binding Sites; D003300:Copper / Q000737:chemistry / Q000378:metabolism*; D006657:Histones / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D009532:Nickel / Q000737:chemistry / Q000378:metabolism*; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*
D006657:Histones; D010455:Peptides; D003300:Copper; D009532:Nickel