Detection of Ascorbate Peroxidase (APX) Activity in Plant Tissues: Using Non-denaturing PAGE and Spectrophotometric Assay.

At the cellular level, the generation of reactive oxygen species (ROS), such as hydrogen peroxide (H 2 O 2 ), due to different abiotic or biotic stress, causes oxidative stress that induces an imbalance in the metabolism. Among the different H 2 O 2 -scavenging enzymatic antioxidants, ascorbate peroxidase (APX) is a heme-peroxidase that plays an important role in the ascorbate-glutathione pathway using ascorbate to reduce H 2 O 2 to water. Using non-denaturing polyacrylamide gel electrophoresis (PAGE) in combination with a spectrophotometric assay for APX activity, the protocol allows identifying diverse APX isozymes present in different organs and plant species.