The impact of two –GlyProGly– motifs on formation of di-copper complexes by His 4 -cyclopeptides

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Two new somatostatin analogs with a characteristic part of the sequence -c(Cys-Phe-Trp-Lys-Thr-Cys)- and with two histidine and two aspartic acid moieties in their structures were synthesized and analyzed in terms of their coordination abilities with copper (II) ions. Both peptides bind Cu(II) effectively. Ligands form 4N complexes with binding mode in a basic range of pH. But in spite of very similar sequences of the two peptides a significant difference in the effectiveness of the binding of copper (II) ions was observed.

Section: Resultssupporting

confidence: 83%

The Coordination Abilities of New Cyclic Analogs of Somatostatin

Marciniak

Cebrat

Brasuń

2016

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“…The stoichiometry of this form shows dissociation of two protons from the peptide molecule. The corrected logβ* = 5.27 is comparable to logβ* = 5.75 of the complex with {2N Im } coordination mode calculated for the cyclopeptide c(HisLysHisGlyProGlyHis LysHisGlyProGly) (Kotynia et al 2014). The formation of the second CuH 2 L complex is associated with proton dissociation from the third His residue, what is supported by logK value (Table 2).…”

Section: Species Parameterssupporting

confidence: 69%

The Analysis of the Structural Aspects of Cu(II) Binding by Cyclic His/Asp-Analogues of Somatostatin

Marciniak

Kotynia

Cebrat

et al. 2019

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Two new somatostatin analogs with a characteristic part of the sequence in their structures,-c(Cys-Phe-Trp-Lys-Thr-Cys)-, were synthesized and analyzed in terms of their coordination abilities with copper(II) ions. Cyclic peptides analyzed in our previous work had histidine and aspartic acid moieties in their structures which were responsible for metal ion coordination. In analyzed molecules these amino acids are also present. Peptides Ac[D 1,2,9,10 ]c(SST) and Ac[H 1,2,9,10 ]c(SST) have four aspartic acid or four histidine moieties, respectively. Both peptides bind Cu(II) effectively. Due to similar structures and the possibility of comparing the obtained results with these for the two previously published, the coordination abilities of two new ligands are possible to propose. Moreover, the effectiveness of copper(II) ion binding by four cyclic His/Asp-analogues of somatostatin is also discussed here. The peptide with four histidine moieties is the most efficient among described ligands.

“…The synthesis of discussed peptide c(HKHGPG) 2 have been described in details in the previously published article (Kotynia et al 2014 ).…”

Section: Experimental Methodsmentioning

confidence: 99%

“…The copper (II) binding by cyclopeptides strongly depends on the acid–base properties of the side chain groups (Czapor et al 2011 ; Matera et al 2008 ), its optical isomerism (Matera et al 2008 ), number of His residues in the peptide chain as well as the size of the peptide ring (Brasuń et al 2009 ). Moreover, the insertion of two Pro amino acid residues in their sequence allows for creating of two well defined binding sites for metal ions (Kotynia et al 2012 , 2014 ). Our previous studies have shown that the presented cyclopeptide (Kotynia et al 2014 ) as well as its analogue with the c(HKHPHKHP) sequence (Kotynia et al 2012 ) are able to form di-copper complexes with the {2N Im , 2 } binding manner observed in the physiological range of pH.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the insertion of two Pro amino acid residues in their sequence allows for creating of two well defined binding sites for metal ions (Kotynia et al 2012 , 2014 ). Our previous studies have shown that the presented cyclopeptide (Kotynia et al 2014 ) as well as its analogue with the c(HKHPHKHP) sequence (Kotynia et al 2012 ) are able to form di-copper complexes with the {2N Im , 2 } binding manner observed in the physiological range of pH. Based on previous studies we decided to characterize the abilities of cyclopeptide with the c(HKHGPG) 2 sequence to form the heteronuclear, Cu(II)/Zn(II) complexes as well as the Cu,ZnSOD-like activity.…”

Section: Introductionmentioning

confidence: 99%

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The Analysis of Cu(II)/Zn(II) Cyclopeptide System as Potential Cu,ZnSOD Mimic Center

Kotynia

Janek

Czyżnikowska

et al. 2017

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In this paper are presented the features of copper (II) and zinc (II) heteronuclear complexes of the cyclic peptide—c(HKHGPG)2. The coordination properties of ligand were studied by potentiometric, UV–Vis and CD spectroscopic methods. These experiments were carried out in aqueous solutions at 298 K depending on pH. It turned out that in a physiological pH dominates Cu(II)/Zn(II) complex ([CuZnL]4+) which could mimic the active center of superoxide dismutase (Cu,ZnSOD). In next step we performed in vitro research on Cu,ZnSOD activity for [CuZnL]4+ complex existing in 7.4 pH by the method of reduction of nitroblue tetrazolium (NBT). Also mono- and di-nuclear copper (II) complexes of this ligand were examined. The ability of inhibition free radical reaction were compared for all complexes. The results of these studies show that Cu(II) mono-, di-nuclear and Cu(II)/Zn(II) complexes becoming to new promising synthetic superoxide dismutase mimetics, and should be considered for further biological assays.