Detection of ROS directly can be difficult, since the half-life of most free radicals is so short. A more reliable and well-published method is to detect the resulting damage caused by ROS. Proteins are a common target of ROS and provide an easy, sensitive method for testing oxidative stress levels.

In this edition we discuss various ways to test for specific protein damage markers. Continue reading for more details.


Protein Carbonyl Assays

The most common products of protein oxidation in biological samples are the carbonyl derivatives of proline, arginine, lysine, and threonine residues. Such derivaties are chemically stable and found universally across all proteins.


Many oxidative stress markers degrade over time, but protein carbonyl content can still be measured reliably even in samples frozen for 1-2 years. 

Our OxiSelect™ Protein Carbonyl Assays allow fast, reliable measurement of protein damage. A variety of formats is available including Western blot, fluorometric, spectrophotometric, and the most popular ELISA kit.

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Nitrotyrosine Assays

The presence of nitric oxide, via the intermediate reactive molecule peroxynitrite, most often results in nitration of tyrosine residues, i.e. formation of 3-Nitrotyrosine in proteins. The 3-Nitrotyrosine marker is extremely stable and easily measured in cell lysates, plasma, or serum.


Our Nitrotyrosine Assay Kits are available in two formats: Western blot and a 96-well competitive ELISA.

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Advanced Glycation End Product (AGE) Assays

AGE modification of proteins can contributeto the pathophysiology of aging and long-term complications of diabetes, atherosclerosis and renal failure.

Our range of AGE assays include an AGE ELISA Kit to broadly detect the formation of advanced glycation end products, as well as ELISA kits to detect specific AGE species: 

Methylglyoxal (MG)