Heavy Metal-binding Peptides Research Articles

The Purification and Rapid Identification of Heavy Metal-binding Peptides of Water Hyacinth

This paper studies the rapid identification of heavy metal-binding peptides (phytochelatin) by taking Water Hyacinth as a model plant. Plants were cultured in water containing 2 μg/ml Cd2+ for 13 days. The Sephadex G-50 chromatography of root extract under low salt concentration (0. 01 mol/L PBS) gave a Cd-binding peak with MW of 10 ,000 determined by SEC HPLC. After oxidation with performic acid, its SEC HPLC molecular weight decreased to below 1300 and the reverse phase HPLC showed one peptide peak, whose amino acid composition is the same as that of the sample never undertaking oxidation, and (Glu/Gln):Cys:Gly=2:2:1. According to the general structure of phytochelatin (γ-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.

Homo-phytochelatins are heavy metal-binding peptides of homo-glutathione containing Fabales

Exposure of several species of the order Fabales to Cd 2+ results in the formation of metal chelating peptides of the general structure (γ-Glu-Cys) n -β-Ala ( n = 2–7). They are assumed to be formed from homo-glutathione and are termed homo-phytochelatins, as they are homologous to the recently discovered phytochelatins. These peptides are induced by a number of metals such as Cd 2+, Zn 2+, Hg 2+, Pb 2+, AsO 4 − and others. They are assumed to detoxify poisonous heavy metals and to be involved in metal homeostasis.