Tetramethylbenzidine (TMB) is an excellent substrate for detecting horseradish peroxidase (HRP) labeled probes. TMB produces a soluble end product which is blue in color that is quantitated at 650nm, providing an ultrasensitive quantitative substrate system.

TMB has been shown to be a safe-sensitive substrate for the assay of horseradish peroxidase (HRP). Initially, in the presence of HRP and hydrogen peroxide, a one-electron oxidation product is formed.

This compound, a cation free radical, is blue in color wth an adsorption maximum at 653nm. Further reaction with HRP/H2O2 or acidification of the radical with acid yields the diimine terminal oxidation product adsorbing light at 450 nm. The extinction coefficient of the radical (E653 nm = 5.9x10e4 mol-1 cm-1) provide a remarkably sensitive system for the assay of HRP and HRP labeled probes.

TMB is a single component reagent stable at room temperature and not sensitive to normal laboratory light. It is optimized with respect to TMB and hydrogen peroxide concentrations and yields a linear response with the concentrations of HRP usually employed in immunologic assays.

Kinetic and Endpoint Assays of Horseradish Peroxidase

After reacting with a HRP labeled probe, tissue sections or blots are incubated in the TMB solution. A one electron oxidation occurs resulting in the formation of a stable blue precipitate at the sites of HRP activity.

• Single component system • Room temperature stable • Exhibits low background levels • Safe to use - no weighing of hazardous powders • Save preparation time - use right out of the bottle • Ultra-low sensitivity • Minimal lot-to-lot variation

Contains TMB, 1.25mM/L in an acetate buffer with proprietary stabilizers and precipitating agents.

Stable for 12 months at RT. To extend the stability of product, refrigerate at 4°C.

This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications without the expressed written authorization of United States Biological.

 All products should be handled by qualified personnel only, trained in laboratory procedures.