Identification of Superoxide Dismutase (SOD) Isozymes in Plant Tissues

Superoxide and hydrogen peroxide are reactive oxygen species (ROS) involved in the oxidation of multiple biological molecules and the signaling processes during plant growth and stress response. Thus, control of ROS is fundamental for cell survival and development, with superoxide dismutase (EC 1.15.1.1, SOD) being one of the main enzymes involved. Different isoforms of SOD catalyze the dismutation of superoxide (O₂^.-) to hydrogen peroxide (H₂O₂) and oxygen (O₂), such as Mn-SODs, Cu,Zn-SODs, and Fe-SODs. Using non-denaturing polyacrylamide gel electrophoresis (PAGE) combined with a specific staining method for SOD activity, the protocol describes the identification of different SOD isozymes, based on their differential inhibition by KCN and H₂O₂, in different organs and plant species such as pea (Pisum sativum L.) leaves and pepper (Capsicum annuum L.) fruits.