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Identification and characterization of Cd-induced peptides in Egeria densa (water weed): Putative role in Cd detoxification

Malec, Przemysław, Maleva, Maria G., Prasad, M.N.V., Strzałka, Kazimierz
Aquatic toxicology 2009 v.95 no.3 pp. 213-221
water pollution, macrophytes, Egeria densa, plant pigments, metabolic detoxification, peptides, cadmium, protein content, thiols
Egeria densa has ability to grow in heavy metal contaminated and polluted bodies of water. Shoots exposed to Cd at concentrations up to 300μM for 7 days showed a pronounced decrease in chlorophyll a and in total protein concentration. Thiol-containing compounds and low-molecular-weight polypeptides were detected in Cd-treated plant extracts by gel filtration chromatography. Two Cd-binding fractions, a thiol-enriched fraction and a non-thiol fraction with a lower molecular weight were identified in extracts by gel filtration. The main fraction of thiol-containing polypeptide, purified by gel filtration and anion-exchange chromatography had a molecular weight of ∼10kDa. This peptide was characterized by a broad absorption band specific to mercaptide bonds and Cd-sensitive fluorescence emission of aromatic amino acid residues. Our results indicate that cadmium exposure of plants resulted in both a formation of thiol-enriched cadmium complexing peptides and a synthesis of low-molecular-weight metal chelators. The putative role of these compounds in Cd detoxification is discussed.