Primary structure of phycocyanin from the unicellular rhodophyte Cyanidium caldarium. I. Complete amino acid sequence of the alpha subunit.

Crystal Structure of C-Phycocyanin from Cyanidium caldarium Provides a New Perspective on Phycobilisome Assembly

“…Methylation of ␤-Asn 72 was also detected as before (Duerring et al, 1991;Klotz et al, 1986). Asn 72 was initially sequenced as Thr (Offner et al, 1981); later this misassignment was corrected when the DNA sequence became available (RFT, unpublished data). The side chain of Asn 72 provides a direct link of the chromophore ␤-84 to solvent.…”

“…Phycobilisomes from C. caldarium contain allophycocyanin (plus linker proteins) in the core and phycocyanin as the only colored protein in the rods. The phycocyanin was purified as described earlier (Offner et al, 1981;Troxler et al, 1981) and concentrated to 15 mg/ml. The purity was measured by the ratio of absorbance at 620 nm (chromophore) and 280 nm (protein) and, in protein samples used for crystallization, was more than 8.…”

Phycocyanin in physical chemical studies

“…The a subunit has one chromophore covalently attached to a cysteine, which is residue 84 from the N terminus, and the 0 subunit has two chromophores attached to cysteines at positions 84 and 155. [115][116][117] The X-ray crystallographic results for phycocyanin provide excellent data on the distances and orientations between the chromophores within a monomer, trimer, and hexamer.63-65 Since the rate of exciton transfer is extremely sensitive to distance (eq 14), careful analysis of each aggregation state and their varying of bilin-to-bilin distances is essential to understand the flow of excitons through the complex bilin matrix of a phycobilisome.…”