Design of histidine containing peptides for better understanding of their coordination mode toward copper(II) by CD spectroscopy

Ida Noemi Jakab, Béla Gyurcsik, Tamás Körtvélyesi, Ilze Vosekalna, Jan Jensen, Erik Larsen

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The systematic investigation of the copper(II) complexes of tripeptides Xaa–Xaa–His, Xaa–His–Xaa and His–Xaa–Xaa, where Xaa = Gly or Ala was performed by combined pH-metry, spectrophotometry, CD and in part EPR spectroscopy. The matrix rank analysis of the spectral data revealed the number of the coloured and optically active species as a basis for the solution speciation. A critical evaluation on the speciation and solution structure of the complexes formed is presented on the basis of their d–d band optical activity. The replacement of a Gly residue with the chiral Ala amino acid allowed us to gain decisive information on the solution structure of the complexes by CD spectroscopy. It was shown that the tripeptides with histidine in the third position formed CuH−2L species with (NH2, 2N−, ImN – where Im stands for imidazole) coordination sphere as a major species, and only the macrochelated CuL complexes as minor species around pH 5.0. In copper(II)–Xaa–His–Xaa tripeptide systems the CuH−1L (NH2, N−, ImN) is the most stable species at physiological pH, but the vacant fourth site around copper(II)ions is offered for further deprotonation, most probably resulting in mixed hydroxo species at low (
Keyword: Speciation,Copper(II)-complexes,CD spectroscopy,Histidine containing peptides
Original languageEnglish
JournalJournal of Inorganic Biochemistry
Volume101
Issue number10
Pages (from-to)1376-1385
ISSN0162-0134
DOIs
Publication statusPublished - 2007
Externally publishedYes

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