Peridinin chlorophyll protein complex (PerCP)-conjugated anti-human primary antibodies are fluorescent immunoreagents widely used in flow cytometry, fluorescence-activated cell sorting (FACS), and multicolor immunophenotyping. PerCP is a naturally occurring light-harvesting pigment-protein complex isolated from dinoflagellates of the genus Dinophyceae (e.g., Glenodinium sp. and Amphidinium carterae). Its exceptional extinction coefficient, high quantum efficiency, and large Stokes shift make it a valuable fluorophore for detecting human cell surface and intracellular antigens, particularly when paired with FITC and PE in multicolor panels.
Structure and Composition of PerCP
PerCP is a water-soluble antenna complex that employs the carotenoid peridinin as its principal light-harvesting pigment. The monomeric form of PerCP from Amphidinium carterae binds eight peridinin molecules and two chlorophyll a (Chl a) molecules, with an apoprotein molecular weight of approximately 32 kDa. The complex exists as a trimer in its native state, resolved at 2 Å resolution, with the central magnesium of the emitting chlorophyll a being monoligated. For antibody conjugation purposes, PerCP is commonly supplied as a 35 kDa monomeric or oligomeric preparation. The chromophores are covalently linked tetrapyrrole prosthetic groups that are protected from quenching by the protein scaffold, conferring high fluorescence quantum efficiency.
Spectral Properties
PerCP exhibits an absorption maximum at approximately 477 nm, with efficient excitation by the 488 nm argon-ion laser line (or blue laser in modern flow cytometers). The emission maximum is at 677–678 nm, giving PerCP a large Stokes shift of approximately 200 nm that minimizes spectral overlap with green and yellow fluorophores. The molar extinction coefficient is exceptionally high at 4.06 × 105 cm−1M−1, reflecting the combined absorptive capacity of the eight peridinin and two chlorophyll chromophores. PerCP is typically detected using a 695/40 nm bandpass filter in flow cytometry.