| Popis: |
Monodehydroascorbate reductase (MDAR; EC 1.6.5.4) is a major enzyme in ascorbate regeneration. Ascorbate plays a central role in reactive oxygen species (ROS) scavenging, in particular at hydrogen peroxide subcellular level regulation through the ascorbate–glutathione cycle. Therefore, MDAR activity contributes to ROS level modulation. ROS content is increased in adverse stress conditions and can be harmful for cells. But ROS are also useful signaling molecules that regulate physiological processes. The numerous MDAR isoforms, their various subcellular localizations and the fact that they come from multigenic families all complicate the understanding of their implications in cell metabolism. Nevertheless, it appears that the various isoforms act in specific conditions, both in case of stress, leading to excessive ROS production, and in physiological processes such as seedling development and photosynthesis. |
