Phycoerythrin is one of a series of fluorescent pigments known as phycobiliproteins, which are produced by red and blue green algae. It occurs in more than one form, and has found application in immunology and diagnostic medicine. B and R Phycoerythrins provide superior labeling compared to fluorescein and rhodamine, and are used for labeling antibodies, usually monoclonals. These dyes may also be coupled to enzymes and other proteins, nucleic acids, polypeptide hormones, drugs, etc. Since phycoerythrins absorb light maximally between 450 and 650nm they fill the need for an intense fluorescent dye in the longer wavelengths of the visible spectrum, thereby avoiding interference from naturally fluorescing biological substances. R Phycoerythrin (240 kDa) is a labile molecule that may dissociate into components upon exposure to reducing or denaturing agents.Synonyms: rpeB