Electronic absorption and electron spin resonance studies on the interaction between the biologically relevant copper(II) glycylglycine and L-histidine complexes with D-penicillamine

Abstract

The ternary systems Cu^II+ Gly-Gly +D-penicillamine, and Cu^II+L-His +D-penicillamine, were examined in neutral aqueous solutions by electronic absorption and e.s.r. spectroscopy. The Gly-Gly system was further examined by circular dichroism and electrophoresis measurements. The results are compared with those from the binary system Cu^II+D-penicillamine, and with the ternary systems where L-cysteine or dimercaptopropanol replace D-penicillamine. Evidence is presented for the formation of dimeric ternary complexes in the Gly-Gly and L-His systems at concentrations of Cu : Pen < 1 : 2. The relevance of the ternary complexes to the mode of mobilisation of the excess copper in Wilson's disease is discussed.