Structural Characteristics
R-phycoerythrin is predominantly produced by red algae. The protein is made up of at least three different subunits and varies according to the species of algae that produces it. The subunit structure of the most common R-PE is (αβ)6γ. The α subunit has two phycoerythrobilins (PEB), the β subunit has 2 or 3 PEBs and one phycourobilin (PUB), while the different gamma subunits are reported to have 3 PEB and 2 PUB (γ1) or 1 or 2 PEB and 1 PUB (γ2). The molecular weight of R-PE is 250,000 Daltons. PE-695 is a tandem fluorophore comprising R-Phycoerythin and a red-shifted cyanine dye.

Spectral Characteristics

• Absorption maximum – 565 nm
• Additional Absorption peak – 498 nm
• Emission maximum – 695 nm