Cadmium binding in mixtures of phytochelatins and their fragments:A voltammetric study assisted by multivariate curve resolution andmass spectrometry

摘要

Phytochelatins (PC_n, (y-Glu-Cys)nGly) are cysteine-rich peptides synthesized by plants which areinvolved in metal bioregulation and phytoremediation. Multivariate Curve Resolution by AlternatingLeast Squares (MCR-ALS) is applied to voltammetric data obtained from the analysis of thecompetitive binding of Cys or Cys-Gly with PC2 or PC3 by Cd". The displacements between ligands, thechain length dependence on the competitive binding to PC,, and the possible existence of mixed ligandmetal-complexes are investigated. The shape analysis of the resulting pure voltammograms andconcentration profiles of the components resolved by MCR-ALS suggests that ligands containing morethiol groups are able to displace the shorter chain ligands from their metal complexes, whereas theopposite does not happen. Electrochemical results are compared with ESI-MS measurements.