Impact of 1,5-disubstituted tetrazole ring on chelating ability of delta-selective opioid peptide.
Complex formation between Cu(II) and three tetrazole analogues of opioid peptide-deltorphin I has been investigated. In potentiometric and spectroscopic (UV-Vis, CD and EPR) studies have been established the thermodynamic stability, speciation and structure of Cu(II) complexes with Tyr-D-Ala-Phe-Asp-Val-Val-Gly-NH2 (L1), Tyr-Psi(CN4)-Gly-Phe-Asp-Val-Val-Gly-NH2 (L2), Tyr-Gly-Psi(CN4)-Phe-Asp-Val-Val-Gly-NH2 (L3) and Tyr-D-Ala-Psi(CN4)-Phe-Asp-Val-Val-Gly-NH2 (L4). The site of the insertion of tetrazole moiety Psi(CN4) into the peptide sequences has critical impact on their co-ordination ability. Comparison of the binding ability of the tetrazole analogues reveals that around physiological pH region the L3 and L4 are more effective ligands for copper(II) than L(1) and L(2). The peptide conformation changes achieved by Cu(II) co-ordination may be essential for binding of the tetrazole deltorphins at the opiate receptors.
Łodyga-Chruścińska
Elzbieta
E
Institute of General Food Chemistry, Technical University of Łódź, ul. Stefanowskiego 4/10, Łódz 90-924, Poland. elalodyg@p.lodz.pl
Ołdziej
Stanisław
S
Micera
Giovanni
G
Sanna
Daniele
D
Chruściński
Longin
L
Olczak
Jacek
J
Zabrocki
Janusz
J
D000595:Amino Acid Sequence; D002614:Chelating Agents / Q000737:chemistry*; D002942:Circular Dichroism; D003300:Copper / Q000737:chemistry / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008958:Models, Molecular; D009842:Oligopeptides / Q000737:chemistry*; D018847:Opioid Peptides / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship; D013777:Tetrazoles / Q000737:chemistry*
D002614:Chelating Agents; D009842:Oligopeptides; D018847:Opioid Peptides; D013777:Tetrazoles; C060208:deltorphin I, Ala(2)-; D003300:Copper