The complex formation of copper(II) with GHL and related peptides

The formation constants for complexes of Cu(II) with GHL and a series of related dipeptides were determined by means of potentiometric titration and ESR spectroscopy in aqueous solution. The complex formation of the related peptides AH, LH, HL, GL and VL is compared to that of GHL. The somewhat higher affinity of GHL to Cu(II) as compared to AH and LH seems to be a poor explanation for the biological functions of GHL. A dimeric Cu(II)HL complex is detected, which displays an ESR spectrum at room temperature. The ESR spectra of the different complexes and the influences of structures on the spectra are discussed.