Stability constants of complexes of copper(II) ions with some histidine peptides

Abstract

Values at 37 °C and 0·15M(KNO₃) for equilibrium constants of copper(II) complexes of glycylhistidine, glycyl-histidylglycine, histidylglycine, and carnosine have been obtained from pH titration data by minimising the computed standard deviation in titre for a range of metal ion and ligand concentrations. Account was taken of the formation of protonated, hydrolysed, and polynuclear complexes as well as of ML_n-type complexes. A comparison is made of the copper-complexing abilities of these peptides in competition with α-amino-acids under physiological conditions.