Similarities and differences of copper and zinc cations binding to biologically relevant peptides studied by vibrational spectroscopies.
GHK and DAHK are biological peptides that bind both copper and zinc cations. Here we used infrared and Raman spectroscopies to study the coordination modes of both copper and zinc ions, at pH 6.8 and 8.9, correlating the data with the crystal structures that are only available for the copper-bound form. We found that Cu(II) binds to deprotonated backbone (amidate), the N-terminus and Nπof the histidine side chain, in both GHK and DAHK, at pH 6.8 and 8.9. The data for the coordination of zinc at pH 6.8 points to two conformers including both nitrogens of a histidine residue. At pH 8.9, vibrational spectra of the ZnGHK complexes show that equilibria between monomers, oligomers exist, where deprotonated histidine residues as well as deprotonated amide nitrogen are involved in the coordination. A common feature is found: zinc cations coordinate to Nτand/or Nπof the His leading to the formation of GHK and DAHK multimers. In contrast, Cu(II) binds His via Nπregardless of the peptide, in a pH-independent manner.
Laboratoire de bioélectrochimie et spectroscopie, UMR 7140, université de Strasbourg, 4 Rue Blaise Pascal, 67000, Strasbourg, France.
Alicia
A
Schirer
Laboratoire de bioélectrochimie et spectroscopie, UMR 7140, université de Strasbourg, 4 Rue Blaise Pascal, 67000, Strasbourg, France.
Youssef
Y
El Khoury
Laboratoire de biométaux et chimie biologie, UMR 7177, université de Strasbourg, 4 Rue Blaise Pascal, 67000, Strasbourg, France.
Peter
P
Faller
Laboratoire de bioélectrochimie et spectroscopie, UMR 7140, université de Strasbourg, 4 Rue Blaise Pascal, 67000, Strasbourg, France. hellwig@unistra.fr.
Petra
P
Hellwig
D000577:Amides / Q000737:chemistry; D001665:Binding Sites; D002412:Cations / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman; D015032:Zinc / Q000737:chemistry*
D000577:Amides; D002412:Cations; D009942:Organometallic Compounds; D010455:Peptides; D003300:Copper; D015032:Zinc
DAHK; GHK; Infrared spectroscopy; Peptide copper coordination; Raman spectroscopy; Zinc coordination