Copper(II) coordination properties of the integrin ligand sequence PHSRN and its new β-cyclodextrin conjugates.
The peptide sequence PHSRN is the second cell binding site of the human fibronectin protein, a glycoprotein which plays a critical adhesive role during development, tissue repair and angiogenesis. The copper(II) complexes with the peptide fragment PHSRN were characterized by potentiometric and UV-visible, CD, EPR spectroscopic methods. Thermodynamic and spectroscopic evidences indicate that at physiological pH, only one copper(II) complex species, [CuLH(-2)], is present and the metal ion is bound to one imidazole and two amide nitrogen atoms (N(Im), 2N(-)) in a tetrahedral distorted square planar coordination. Two new β-cyclodextrin-ethylendiamino derivatives with the PHSRN covalently attached were synthesized as multitargeting molecules, able to have a site-specific recognition sequence, to interact with copper(II) ions and to be a potential carrier of hydrophobic drugs. Copper(II) complexes with these β-cyclodextrin derivatives were characterized by means of potentiometric and spectroscopic techniques. The comparison of the experimental parameters determined at different pH values with those obtained for the parent peptide complex species, shows that at physiological pH the ethylendiamino-β-CD moiety does not influence the peptide interaction with copper ions and the β-CD hydrophobic cavity is not blocked, being available to host hydrophobic drugs such as naproxen.
Istituto di Biostrutture e Bioimmagini-CNR-Catania, Viale A. Doria 6, 95125 Catania, Italy.
Antonio
A
Magrì
Franca
F
D'Alessandro
Donatella A
DA
Distefano
Tiziana
T
Campagna
Giuseppe
G
Pappalardo
Giuseppe
G
Impellizzeri
Diego
D
La Mendola
D001665:Binding Sites; D002413:Cations, Divalent; D002942:Circular Dichroism; D056831:Coordination Complexes / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D004337:Drug Carriers / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D005029:Ethylenediamines / Q000737:chemistry; D005353:Fibronectins / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D016023:Integrins; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D009288:Naproxen / Q000737:chemistry; D009842:Oligopeptides / Q000737:chemistry*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics; D047392:beta-Cyclodextrins / Q000737:chemistry*
D002413:Cations, Divalent; D056831:Coordination Complexes; D004337:Drug Carriers; D005029:Ethylenediamines; D005353:Fibronectins; D016023:Integrins; D008024:Ligands; D009842:Oligopeptides; D047392:beta-Cyclodextrins; D009288:Naproxen; C031234:ethylenediamine; D003300:Copper