Investigation of Pb( ii ) binding to pectin in Arabidopsis thaliana

Phytochelatins and glutathione are known as the most common peptides responsible for binding with toxic metals in plants, but recently the role of other bioligands, such as proteins, organic acids, flavonoids and oligosaccharides, has received renewed attention. Size-exclusion chromatography (SEC) coupled to ICP-MS and electrospray MS were applied for the analysis of lead species synthesised by Arabidopsis thaliana, a model genetic plant. Lead was found to be accumulated mainly in roots (9.6 ± 0.1 μg of Pb per g of the dry mass) and showed good affinity to galacturonic acid, the main component of two pectin domains homogalacturonan and rhamnogalacturonan I. The results demonstrate the potential application of SEC-ICP-MS and SEC-ESI-MS as a complementary and efficient approach to study toxic heavy metals in biological systems.