TMB is a substrate for horseradish peroxidase. Develops a soluble blue reaction product that may be read at 370 or 655 nm. For endpoint assays the reaction may be stopped with acid, forming a yellow reaction product that may be read at 450 nm. Recommended for ELISA (microwell) procedures, not recommended for membrane applications. 3,3′,5,5′-Tetramethylbenzidine (TMB) Liquid Substrate System for ELISA has been used as a substrate for horseradish peroxidase antibody conjugate for detecting hendra virus glycoprotein, tetracosactide, sIgA and neutrophil extracellular traps (NETs).