Oxidative stress has been implicated in the pathogenesis of neurodegenerative disorders, cancer, and aging. Oxidative stress occurs as a response to increased oxidants, decreased anti-oxidants, or failure to repair oxidative damage induced by reactive oxygen species (ROS). ROS are free radicals, reactive molecules containing oxygen, or molecules containing oxygen that generate free radicals. ROS include nitric oxide (NO), superoxide (O2-), peroxynitrite (ONOO-), and hydroxyl radical (OH-). ROS are cleared from cells by the action of superoxide dismutase (SOD), catalase and peroxidases.
NO, produced by nitric oxide synthases (NOS), is a critical signaling molecule involved in many physiological processes including muscle contraction, vasodilation, neuronal transmission, and immune responses. Some of these effects are mediated through reaction with and activation of guanylate cyclase (GC), resulting in increased cGMP production. With a half-life of seconds, NO readily diffuses through the cytosol and cell membrane, allowing it to act inside or adjacent to the cell in which it was produced.
ROS may interact to form agents that modify cellular proteins. Superoxide, produced by NADPH oxidase (phox), reacts with NO to form peroxynitrite. Intracellular peroxynitrite can modify proteins by interacting with and nitrating tyrosine residues to form 3-nitrotyrosine. Tyrosine nitration may increase (e.g. sGC, Src, PI3K, Akt), decrease (e.g. Mn-SOD, Ca++-ATPase), or have no discernable effect (e.g. p53, VASP, α-Synuclein) on the activity of a particular protein.
Upstate's new Nitrotyrosine Assay Kit, Chemiluminescence Detection (Cat. # 17-376) is a competitive ELISA for the quantitation of tyrosine nitration. The kit includes all reagents needed for measurement of tyrosine nitration, including white high binding 96-well plates, nitrated BSA standard, a Nitrotyrosine antibody, LumiGLO® chemiluminescent detection substrate, and wash buffers.
The assay has a wide dynamic range and high precision, making this assay a valuable new tool for the study of tyrosine nitration.