THE PURIFICATION AND RAPID IDENTIFICATION OF HEAVY METAL-BINDING PEPTIDES OF WATER HYACINTH

This paper studies the rapid identification of heavy metal-binding pep tides (phytochelatin) by taking Water Hyacinth as a model plant. Plant s were cultured in water containing 2 mug/ml Cd2+ for 13 days. The Sep hadex G-50 chromatography of root extract under low salt concentration (0. 01 mol/L PBS) gave a Cd-binding peak with MW of IQ,000 determined by SEC HPLC. After oxidation with performic acid, its SEC HPLC molecu lar weight decreased to below 1300 and the reverse phase HPLC showed o ne peptide peak, whose amino acid composition is the same as that of t he sample never undertaking oxidation, and (Glu/Gln):Cys,Gly=2:2:1. Ac cording to the general structure of phytochelatin (gamma-Glu-Cys)n-Gly , n is 2 in this case. The protocol including the sequential steps of Sephadex G-50 chromatography-performic acid oxidation-->reverse phase HPLC-->amino acid analysis is a rapid and effective method to identify the existence of phytochelatin and determine its values of n.