Hydroxyl radical generation and carbon centre depletion in the root cell wall isolate enriched with copper

Abstract

Copper is often accumulated in contaminated soils such as open cast mines, and is toxic to plants. Effect of excess Cu (20 μM) on free radicals generation in the cell wall was investigated in the root cell wall isolated from Verbascum thapsus L. plants. Electron paramagnetic resonance (EPR) spectroscopy of cell wall isolates containing the spin-trapping reagent, 5-diethoxyphosphoryl-5-methyl-1-pyrroline- N-oxide (DEPMPO), was used for detection and differentiation between free radicals. EPR analysis showed an increase of DEPMPO/OH adduct concentration induced by Cu accompanied by the decrease of concentration of carbon center (DEPMPO/CH3) adduct originally determined in the cell wall of control plants. This reaction was suppressed by boiling the cell wall with SDS to denaturate proteins. We show that Cu induced •OH accumulation in the cell wall is enzyme dependent.