The Metal Complexes of Peptides and Related Compounds.

The complex formation between copper(I) ions and glycylglycylglycine (H2A+) has been studied in 3.0 M NaClO4 medium at 25° by constant current coulometry using copper amalgam and glass electrodes. In each series of measurements the copper iota were generated into the ligand solution by electrolysis of two phases copper amalgam. The data, shown in Table 2, were treated by graphical methods and by the least squares computer program, Letagrop. It is concluded that the results obtained are consistent by assuming the equilibria Multiple line equation(s) cannot be represented in ASCII text. where β is an equilibrium constant. It is assumed that the copper(II)-equilibria, reported in the previous paper of this series, coexist in solution. On the bask of the equilibrium constants it may be deduced that for pH higher than 6.5 the principal copper(I) complex is CuICuIIH-3A22-. The standard oxidationreduction potential at pH 7 for the formation of this species from its copper(II) analogue, Cu2H-4A22-, was calculated to be +340 mV. [ABSTRACT FROM AUTHOR]