Enzymatic Methods

Enzymes are important entities in oxidative stress and play multiple functions at different levels. Some pro-oxidant/anti-oxidant enzymes, normally present intracellularly, are found in the blood circulation and thus can be assessed and used as biomarkers of oxidative stress (e.g., myeloperoxidase (MPO), xanthine oxidase (XO), nitric oxide synthases (NOS), glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD), thioredoxin reductase (TrxR), catalase (CAT)). Assays for activity assessment of these enzymes are now available on the market and are widely used in research. Besides, certain enzymes can be used as reagents to assess the level of some reactive species (RS) (e.g., hydrogen peroxide and glutathione (GSH)) in situ. This chapter provides a valuable information and a laboratory resource for oxidative stress assessment using simple and low-cost methodology. We examine in this chapter the molecular basis of each enzymatic reaction with especial emphasis on its limitations and advantages.