TMB Substrates

TMB (3,3’,5,5’-Tetramethylbenzidine) is a substrate for horseradish peroxidase (HRP), a common label conjugated to antibodies for applications such as immunohistochemistry, western blotting, and ELISA. The combination of HRP and hydrogen peroxide causes the oxidation of TMB, resulting in the formation of a blue color. This colorimetric change can be measured at wavelengths between 370 nm to 650 nm. TMB is photosensitive and should be kept away from direct light.