ABSTRACT
Biliproteins were named for their colors; phycocyanins were blue and phycoerythnns were red. To distinguish between biliproteins from red algae and cyanobacteria the prefixes R and C were introduced, example R-phycocyanin, C-phycocyanin, R-phycoerythrin, and C-phycoerythrin. Allophycocyanin has an absorption maximum at about 650 nm and a fluorescence emission maximum at 660 nm. Isolated phycobilisomes have an emission maximum near 675 nm. The visible absorption spectra of C- and R-phycocyanin differ in that the latter has a second absorption maximum at 555 nm along with the 615-nm maximum they share. The R-phycocyanin absorption spectrum was first published in 1910. The protein had the same 11.4 and 6.2S aggregates as C-phycocyanin. The unique spectrum of phycoerythrocyanin was produced from a mixture of bilins: phycocyanobilin and cryptoviolin. The cryptoviolin chromophore had a characteristic UV band at 332 nm. The fluorescence emission maxima of allophycocyanin monomers and trimers were also characteristic with the monomer at 642 nm and the trimer at 660 nm.
