Samples (2 mL) were then applied to an equilibrated Sephadex G-15 gel (GE Healthcare Bio-Science, Uppsala, Sweden) filtration column (50 1.5 cm internal diameter) and were eluted at 1 mL/min with 0.1-M aqueous NaCl solution. Fractions were collected every 4 min. Cd concentrations and absorbance (280 nm) of fractions were analysed using ICP–AES and spectrophotometry (UV-1800; Shimadzu Corporation), respectively. Amino acids and peptides were analysed in 80-lL fractions after mixing with 80 lL of 1 g/100 mL ninhydrin solution and 1.84 mL of distilled water and heating in boiling water for 15 min (Takeuchi et al., 2001). Absorbance was then measured at 570 nm using a spectrophotometer.