Department of Chemistry. A P. S. University, Rewa-486 003 Manuscript received 14 September 1992 Complex formation between copper(II) and triglycine has been studied polarographically in aqueous sodium perchlorate medium The results have been interpreted in terms of various species suggested by Martell et al.2 and Sarkar et al.3 Present findings favour the structures suggested by .Sarkar et al.3. It has also been concluded that even in the physiological pH-range the species may undergo bonding site interconversion causing large changes in the redox property of copper. This may offer an explanation to the considerable variability in redox behaviour of type-2 copper in copper proteins.