Application of High-Performance Liquid Chromatography/ Inductively Coupled Plasma Mass Spectrometry to the Speciation of Cadmium-Binding Metallothionein-like Protein in a Cyanobacterium

Abstract

A metal-binding metallothionein-like protein in a cyanobacterium, Anacystis nidulans R-2, has been spectated by high- performance gel permeation liquid chromatography combined with inductively coupled plasma mass spectrometry (HPLC-ICP/MS). Cadmium-stressed culturing induced a characteristic water-soluble protein in the cyanobacterium. The protein had an apparent molecular weight of ca. 10000, and contained predominantly cadmium as well as smaller amounts of copper and zinc. The cysteine residues in the protein were quantitated on ²⁰²Hg chromatograms after modifying the sulfhydryl groups with p-chloromercuribenzoate. The present findings demonstrate that the HPLC- ICP/MS technique has high potential for the trace level speciation of heavy metal-binding proteins of environmental interest in living organisms.