Assay of plant antioxidants such as catalase and peroxidase ascorbate does not need to determine the protein content in plant extracts, since your study determines the activity of the antioxidant enzymes which is the most important ... that is, the activity is high or low, but if your study isolated these enzymes then the protein content must also be determined with activity.

Kat Ml

its important to quantify protein because acrivity of theses enzymes express per mg of protein

Hello ... Most of biotic and abiotic stresses affect on the level of protein production in plant, either positively or negatively depending on the type of stress, this indicator may constitute an important guide for understanding the extent of the cell's enzyme system being affected by stress especially antioxidant enzymes.