ABSTRACT
Biliproteins are photosynthetic antenna pigments found in cyanobacteria, red algae, and the cryptomonads. These chromoproteins harvest solar energy in regions of the visible spectrum having low chlorophyll absorption and then transfer this excitation energy to chlorophyll in the photosynthetic membrane. Biliproteins are named primarily for their colors. Phycoerythrins have absorption maxima between 498 and 568 nm and are red, the blue phycocyanins absorb at lower energies, and allophycocyanins absorb at still lower energies. CU-Phycoerythrin is the most recently discovered group of phycoerythrins and is prefixed "CU" to indicate its cyanobacterial origins and the presence of a urobilin-like chromophore not found in C-phycoerythrin. The sensitizing chromophores absorbed photons at higher energies and transferred them to the fluorescing chromophores. When isolated from other members of the excitation energy transfer chain, fluorescing chromophores do three things: receive energy from sensitizing chromophores, absorb photons directly, and fluoresce.
