Redox Systems of the Plant Cell Vacuole

The facts presented in a number of investigations suggest that some well-known redox systems are present in the central vacuole. For example, ascorbic acid (AsA), as also ascorbate-dependent enzymes has been identified in the vacuoles of some plants. These facts allow the authors assume the fact of functioning of the ascorbate system in the vacuolar compartment. Furthermore, in the vacuoles of some plants, glutathione and glutathione-dependent enzymes have also been identified. Therefore, the glutathione system can function within the vacuole. The vacuoles accumulate phenolic compounds (PhO), which are substrates for vacuolar phenolic peroxidases (POXs). These enzymes are known to reduce hydrogen peroxide. Together with AsA and POXs, PhO form the redox system of POX/PhO/AsA (PPA) reducing H₂O₂. PPA system is considered as typical for the plant cell vacuolar compartment. Obviously, in the plant cell vacuole, there is the system of antioxidant defense including the ascorbate system, the glutathione system and the PPA system.