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Chelating ability of proctolin tetrazole analogue

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Łodyga-Chruścińska E., Sanna D., Micera G., Chruściński L., Olejnik J., Nachman R. J., Zabrocki J.

Acta Biochimica Polonica

2006

vol. 53

issue 1

65-72

The aim of the investigation was to establish the chelating ability of a new proctolin analogue of the sequence Arg-Tyr-LeuΨ[CN4]Ala-Thr towards copper(II) ions. The insertion of the tetrazole moiety into the peptide sequence has considerably changed the coordination ability of the ligand. Potentiometric and spectroscopic (UV-Vis, CD, EPR) results indicate that the incorporation of 1,5-disubstituted tetrazole ring favours the formation of a stable complex form of CuH-1L. This 4N coordination type complex is the dominant species in the physiological pH range. The tetrazole moiety provides one of these nitrogens. The data indicate that Cu(II) ions are strongly trapped inside the peptide backbone. These findings suggest that Cu(II) can hold peptide chains in a bent conformation. This bent conformation may be essential for bioactivity of the tetrazole peptides.

Effect of tetrazole moiety on coordinating efficiency of deltorphin.

100%

Łodyga-Chruścińska E., Ołdziej S., Micera G., Sanna D., Chruściński L., Olczak J., Zabrocki J.

Acta Biochimica Polonica

2004

vol. 51

issue 1

93-106

A study of the effect of the tetrazole moiety, a cis-amide bond surrogate, on the Cu(II) coordinating properties of oligopeptides is reported. Insertion of the tetrazole moiety Ψ[CN4] into the peptide sequence of [D-Ala2]deltorphin I changes considerably the coordination ability of the peptide. Potentiometric and spectroscopic results show that if the tetrazole moiety is in a suitable position in the peptide chain, i.e. it follows the second residue, a stable CuL species involving 3N coordination is formed in the physiological pH range. The tetrazole Ψ[CN4] ring provides one of these nitrogens. The data indicate that Cu(II) ions are strongly trapped inside a bent peptide backbone. The peptide conformation changes achieved by Cu(II) coordination may be essential for the binding of tetrazole deltorphins at opiate receptors.

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2 Acta Biochimica Polonica

1 2006

1 2004

2 Chruściński L.

2 Micera G.

2 Sanna D.

2 Zabrocki J.

2 Łodyga-Chruścińska E.

1 Nachman R. J.

1 Olczak J.

1 Olejnik J.

1 Ołdziej S.

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Chelating ability of proctolin tetrazole analogue

Effect of tetrazole moiety on coordinating efficiency of deltorphin.