The reduction of cupric ions by the peptides was followed using the Pierce BCA protein assay kit. The peptides (5 mM) in carbonate buffer (pH 10.5, 25 mM) were mixed with CuCl2 (5 mM). The kit's reagents A and B were mixed at a 50:1 ratio and the peptide samples (4 µL) were mixed with the reagents (32 µL). The solutions were left for 30 min before measuring the absorbance of BCA-Cu + at 562 nm using a Biotek Synergy H1 plate reader (Lumitron).