Alkaline Phosphatase (AP) is a reporter enzyme commonly used in immunoassays to detect target antigens in a variety of biological samples. Similar to HRP secondary antibodies, AP-conjugates act as secondary detection agents for Western Blotting (WB), ELISA and IHC applications. Specifically, AP catalyses the dephosphorylation of chromogenic or chemiluminescent substrates to produce coloured or luminescent derivatives respectively. By conjugating the regenerative AP reaction to polyclonal secondary antibodies, this detection method achieves excellent signal amplification. This enables target antigens to be visualised with high specificity and sensitivity. Furthermore, similar to HRP detection, the AP substrate-conversion reaction is linear, generating a signal with magnitude proportional, both, to incubation time and the amount of antigen present. Major distinctions between AP and HRP-based substrate conversion relate to the rapidity and stability of signal generation. Although the AP reaction is slower, the end products are longer-lasting, minimising signal fade. AP conjugates are particularly favoured by researchers processing samples with high endogenous peroxidase activity, since this avoids interference observed in HRP systems. Explore our portfolio of full length and fragmented AP-conjugated secondary antibodies below, that are raised against a variety of primary antibody host species and their isotypes. Many of our antibodies are also available cross-adsorbed - to limit cross-species reactivity and increase the specificity of detection.