ISBN: 978-83-60043-10-3 - eurobic9

Eurobic9, 2-6 September, 2008, Wrocław, Poland
P13. Copper(II) Complexes of Alloferons 1 and 2; a Combined
Potentiometric and Spectroscopic Studies
Ł. Biega, T. Kowalik-Jankowska, M. Kuczer, D. Konopińska
Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383 Wrocław, Poland,
e-mail: TerKow@wchuwr.chem.uni.wroc.pl
Among the bioactive peptides/polypeptides that have already been characterized from insects, antimicrobial
peptides are fascinating scientists for their potential use as therapeutic agents. However, relatively little data are
available on molecules from insects with antiparasitic, antiviral, and/or antitumoral activities. Most available
antiviral and antitumor agents have been derived from plant, microbes, and, to a lesser extent, animal secondary
metabolites.. Two peptides were isolated from the blood of an experimentally infected insect, the blow fly
Calliphora vicina (Diptera), with the following amino acid sequences: HGVSGHGQHGVHG (alloferon 1) and
GVSGHGQHGVHG (alloferon 2).
Many essential metal ions act as the important factor influencing the structure of natural and synthetic
oligopeptides and as a consequence they may have critical impact on their biological activity.
In this presentation we report the results of combined spectroscopic and potentiometric studies on the copper(II)
complexes of the alloferons 1 and 2 and their analogues with N-terminal amine protected group by acetylation.
The peptides involved in the study are: alloferon 1, HGVSGHGQHGVHG; alloferon 2, GVSGHGQHGVHG;
Ac-alloferon 1, Ac-HGVSGHGQHGVHG and Ac-alloferon 2, Ac-GVSGHGQHGVHG. This study was
performed in order to examine the binding ability, especially the effect of the N-terminal amine group on the
formation of complexes with copper(II) ions by the peptides containing three and four histidine residues in the
peptide chain. 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.
The N-terminal amino group of the alloferons 1 and 2 takes part in the coordination of the metal ion.
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