AbstractThe asymmetric structures of poly‐L‐lysine‐copper(II) complex (PLL‐Cu(II)) were investigated and discussed in detail. The CD spectrum of PLL‐Cu(II) has four peaks, three peaks, and one peak at the wave‐length of 650–350, 350–240, and 222 mμ, respectively. These optical active transitions can be assigned to be due to d‐d transitions of cupric ions, charge transfer transitions of cupric complexes and n‐π*transition in a helical polypeptide, respectively. The first two groups of CD bands could be ascribable to the asymmetric coordination structures of ligands to cupric ions. The IR spectra of PLL‐Cu(II) showed a band around 1610 cm−1, which suggested that the peptide amide nitrogens coordinate to the cupric ions with displacements of protons. From these results, it was concluded that the asymmetries of the copper complex unit in the PLL‐Cu(II) is due to the coordination of the peptide amide nitrogens. A structure is presente