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Interaction of Ni(II) and Cu(II) with a metal binding sequence of histone H4: AKRHRK, a model of the H4 tail

Zoroddu, Maria Antonietta and Kowalik-Jankowska, Teresa and Kozlowski, Henryk and Molinari, Henriette and Salnikow, Konstantin and Broday, Limor and Costa, Max (2000) Interaction of Ni(II) and Cu(II) with a metal binding sequence of histone H4: AKRHRK, a model of the H4 tail. Biochimica et Biophysica Acta. General Subjects, Vol. 1475 (2), p. 163-168. ISSN 0304-4165. Article.

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DOI: 10.1016/S0304-4165(00)00066-0

Abstract

Chromatin proteins are believed to represent reactive sites for nickel binding. The unique structure of the N-terminal tail of histone H4 contains sites for post-translational modification close to a histidine residue capable of anchoring binding sites for metal ions. We have analyzed as a minimal model for the H4 tail, the blocked peptide CH3CO-AKRHRK-CONH2 for nickel and copper binding. Ultraviolet–visible, circular dichroism, electron paramagnetic resonance and nuclear magnetic resonance spectroscopic analysis showed that histidine acts as an anchoring metal binding site. A 1N complex is formed between pH=5–7 and 4–6 for Ni(II) and Cu(II), respectively, while at a higher pH a series of 4N complexes are formed. Above pH 8, the 2N high-spin octahedral resulted in a 4N low-spin planar Ni(II) complex. The stability constants of the Cu(II) (3N, 4N) and Ni(II) (4N) complexes with the peptide model of the H4 were distinctly higher than those for a similar blocked peptide with a histidine in the fourth position. Significant shifts in the αproton region in the 1H NMR spectrum of the 4N Ni-complex showed that the conformation of the peptide had been dramatically affected following Ni(II) complexation.

Item Type:Article
ID Code:5305
Status:Published
Refereed:Yes
Uncontrolled Keywords:Ni(II), Cu(II), histone H4, AKRHRK peptide
Subjects:Area 03 - Scienze chimiche > CHIM/03 Chimica generale e inorganica
Divisions:001 Università di Sassari > 01 Dipartimenti > Chimica
Publisher:Elsevier
ISSN:0304-4165
Copyright Holders:© 2000 Elsevier Science
Deposited On:12 Jan 2011 10:10

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