Monobromobimane

Monobromobimane (mBBr) is the most popular thiol-reactive fluorogenic probe. While bromobimane itself is essentially nonfluorescent, it alkylates thiol groups, displacing the bromine and adding the fluorescent tag to the thiol. It is cell-permeable, reacts rapidly at physiological pH with available thiol groups, and generates a stable fluorescent signal. Monobromobimane can be used to evaluate or quantify a variety of compounds containing reactive sulfur or thiol groups, including H2S, glutathione, proteins, and nucleotides. The absorption and emission maxima for monobromobimane are 398 and 490 nm, respectively. mBBr is commonly applied in redox biology research to monitor intracellular thiol status, oxidative stress, and antioxidant capacity, as well as in enzymatic activity assays involving thiol-containing proteins.