Tetramethylbenzidine, chromogen

Substrate S specific to the enzyme is then added along with a chromogen C (e.g. tetramethylbenzidine) that is designed to react with the product of the enzymatic reaction of S. 

After the incubation, the unbound molecules are washed away, leaving behind the bound ones, anchored onto the antibody sites. Now a clear solution of a colorforming reagent (chromogenic substrate) such as, 3,3, 5,5 -tetramethylbenzidine is added to the mixture. The enzyme conjugate, bound to antibody sites on the wall, reacts with the chromogenic substrate forming a blue color. The enzyme catalyzes the transformation of the substrate into a product which reacts with the... 

Bos E, van der DoelanA, van RooyN, Schuurs A (1981) 3,3 ,5,5 -tetramethylbenzidine as an Ames test negative chromogen for horseradish peroxidase in enzyme-immunoassay. J Immunoassay 2 187-204... 

Chromogen solution Tetramethylbenzidine in organic solution. Store at 2-8°C. 

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