title: Isolation and characterization of disc-shaped phycobilisomes from the red alga Rhodella violacea.
abstract: Disc-shaped phycobilisomes were purified from Triton X100 treated cell homogenates of the unicellular marine red alga, Rhodella violacea. Their absorption spectrum had principal maxima at 544 and 568 nm (B-phycoerythrin), 624 nm (C-phycocyanin) and a distinct shoulder at 652 nm (allophycocyanin). Intermolecular energy transfer within the phycobilisomes was clearly demonstrated by fluorescence data. Excited at 546 nm intact phycobilisomes showed a main fluorescence emission maximum at 665 nm, a minor one at 577 nm and a shoulder at 730 nm. Dissociated phycobilisomes revealed a composition of 58% B-phycoerythrin, 25% C-phycocyanin and 17% allophycocyanin under the cultural conditions used. Analytical methods resolved no other components than phycobiliproteins. In addition to the defined C-phycocyanin and two isoproteins of B-phycoerythrin a stable heterogeneous aggregate of B-phycoerythrin/C-phycocyanin was separated in considerable amounts. In the electron microscope negatively stained phycobilisomes appeared as elliptical aggregates having dimensions  slightly above the values found in ultrathin sections and a detailed subunit structure. All observations and data suggest a new rhodophytan phycobilisome type in Rhodella violacea.
mesh_terms: D002458:Cell Fractionation; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D008854:Microscopy, Electron; D045524:Phycobilisomes; D010798:Phycocyanin / Q000032:analysis; D010799:Phycoerythrin / Q000032:analysis; D010860:Pigments, Biological / Q000032:analysis*; D000461:Rhodophyta / Q000032:analysis / Q000648:ultrastructure*; D013053:Spectrophotometry
chemical_list: D045524:Phycobilisomes; D010860:Pigments, Biological; D010798:Phycocyanin; D010799:Phycoerythrin