title: An extremely stable Ni(II) complex derived from the hydrolytic cleavage of the C-terminal tail of histone H2A.
abstract: The C-terminal blocked tetrapeptides SHHK- and SAHK-, which represent the fragments produced from the hydrolysis of the hexapeptides' -TASHHK-, -TESHHK-, and -TESAHK- complexes with Ni(II), were synthesized and their interactions with Ni(II) ions were studied potentiometrically and spectroscopically. Both tetrapeptides interact strongly with Ni(II) ions leading to square-planar complexes with 4N {NH(2),2N(-),N(im)} coordination. The stability of the Ni-SHHK- complex is about 2 orders of magnitude higher than the Ni-SAHK- complex. Spectroscopic evidence and theoretical predictions suggest the positioning of the free imidazole ring, in the Ni-SHHK- complex, above the coordination plane, explaining the extra stability of the complex.
authors.affiliation: Department of Chemistry, University of Ioannina, GR 451 10 Ioannina, Greece.
authors.forename: Marios
authors.initials: M
authors.lastname: Mylonas
authors.forename: John C
authors.initials: JC
authors.lastname: Plakatouras
authors.forename: Nick
authors.initials: N
authors.lastname: Hadjiliadis
authors.forename: Konstantinos D
authors.initials: KD
authors.lastname: Papavasileiou
authors.forename: Vasilios S
authors.initials: VS
authors.lastname: Melissas
mesh_terms: D000595:Amino Acid Sequence; D004355:Drug Stability; D006657:Histones / Q000138:chemical synthesis / Q000737:chemistry*; D006868:Hydrolysis; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry*; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D006657:Histones; D009842:Oligopeptides; D010446:Peptide Fragments; D009532:Nickel