Ascorbic acid and the oxidative processes in pea root cell wall isolates: characterization by fluorescence and EPR spectroscopy.

A comparative fluorescence and oxygen radical-sensitive spin trap EPR spectroscopic study of isolated cell walls (with proteins or deproteinated), in the presence and absence of ascorbate and H(2)O(2) is presented. Fluorescence spectra indicate the presence of at least two fluorophores, one degraded and the other synthesized after reduction or oxidation, indicating phenol di/polymerization. DEPMPO spin trap measurements show that isolated cell walls are capable of oxygen-dependent hydroxyl radical generation in the absence of NADH or other reductants, ascorbate addition, or deproteination of the cell wall abolishing the signal due to hydroxyl radicals.