ELISA Substrates

Various substrates for ELISA kits are available from multiple suppliers. Most ELISAs (enzyme-linked immunosorbent assay) utilize detection antibodies that are labeled with horseradish peroxidase (HRP) or alkaline phosphatase (AP). In order to detect and measure the amount of antigen, these enzymes require the appropriate substrate compound. TMB and ABTS are chromogenic substrates for HRP, producing blue and green colors, respectively. pNPP is an AP substrate that produces a yellow color change. Amplex® Red is a fluorometric HRP substrate with excitation and emission wavelengths at 530 nm and 580 nm, respectively.