Chelating ability of proctolin tetrazole analogue.
The aim of the investigation was to establish the chelating ability of a new proctolin analogue of the sequence Arg-Tyr-LeuPsi[CN(4)]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(-1)L. 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.
Institute of General Food Chemistry, Technical University of Łódź, Łódź, Poland. elalodyg@p.lodz.pl
Elzbieta
E
Łodyga-Chruścińska
Daniele
D
Sanna
Giovanni
G
Micera
Longin
L
Chruściński
Jadwiga
J
Olejnik
Ronald J
RJ
Nachman
Janusz
J
Zabrocki
D002614:Chelating Agents / Q000494:pharmacology*; D002942:Circular Dichroism; D003300:Copper / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D004583:Electrons; D006863:Hydrogen-Ion Concentration; D007477:Ions; D008956:Models, Chemical; D009479:Neuropeptides / Q000494:pharmacology*; D009584:Nitrogen / Q000737:chemistry; D009842:Oligopeptides / Q000494:pharmacology*; D011199:Potentiometry; D013053:Spectrophotometry; D013696:Temperature; D013777:Tetrazoles / Q000494:pharmacology*; D014466:Ultraviolet Rays
D002614:Chelating Agents; D007477:Ions; D009479:Neuropeptides; D009842:Oligopeptides; D013777:Tetrazoles; C045574:1H-tetrazole; C011536:proctolin; D003300:Copper; D009584:Nitrogen