Allophycocyanin (APC) is a phycobiliprotein isolated from Spirulina sp., a blue-green alga. Like other phycobiliproteins, APC is fluorescent, with an extremely high absorptivity and a high quantum efficiency. Our APC-iFluor® 750 Tandem is an excellent replacement for APC-Cy7® and APC-Alexa Fluor® 750 Tandem due to their similar spectral properties. Our APC-iFluor® 750 Tandem is more photostable than APC-Cy7® Tandem. ReadiUse™ Preactivated APC-iFluor® 750 Tandem is an activated APC protein, and can be easily conjugated to antibodies with much higher conjugation yield than the conventional APC.