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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.