Biliprotein assembly in the hemidiscoidal phycobilisomes of the thermophilic cyanobacteriumMastigocladus laminosusCohn. Characterization of dissociation products with special reference to the peripheral phycoerythrocyanin-phycocyanin complexes
✍ Scribed by Michael Nies; Werner Wehrmeyer
- Book ID
- 104760678
- Publisher
- Springer
- Year
- 1981
- Tongue
- English
- Weight
- 855 KB
- Volume
- 129
- Category
- Article
- ISSN
- 0302-8933
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✦ Synopsis
The dissociation products of isolated phycobilisomes of Mastigocladus laminosus were separated and analyzed by ultracentrifugation and, in part, by isoelectric focusing. With the exception of the allophycocyanin core, the sedimentation constants of peripheral phycocyanin-and phycoerythrocyanin-phycocyanin complexes lay in the range of 6 to 17 S. The latter was represented by a 17 S aggregate of two hexameric phycocyanins (dodecamer, dipartite unit). A complex with an absorption maximum at 610rim (phycocyanin) and a shoulder at 580nm (phycoerythrocyanin), a fluorescence emission maximum at 645 nm and a sedimentation constant of 11 S is described as a heterogeneously composed hexamer of (afi)3-phycoerythrocyanin-(afl)3phycocyanin. It was stable under extended dissodation in the cold and under isoelectric focusing. An aggregate of 14 S with an absorption maximum at 576 nm and a shoulder in the fluorescence emission spectrum at 625nm (phycoerythrocyanin) in addition to the maximum at 645 nm (phycocyanin) is interpreted as a polar phycoerythrocyanin/ phycoerythrocyanin-phycocyanin complex. Combining these complexes with phycocyanin dodecamers creates peripheral rods of the phycobilisome. A proposal of the phycobiliprotein distribution within the phycobilisome of M. laminosus is presented.