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Characterization and structural properties of the major biliproteins of Anabaena sp.

Abstract：

:Studies are presented of the biliproteins of Anabaena sp. This filamentous cyanobacterium contains three major biliproteins. Whereas two of these, C-phycocyanin and allophycocyanin, are common to all cyanobacteria, the third, phycoerythrocyanin (gammamax approximately 568 nm) has hitherto not been described and its distribution among cyanobacteria appears to be limited. Anabaena variabilis and Anabaena sp. 6411 allophycocyanin, C-phycocyanin, and phycoerythrocyanin were purified to homogeneity and characterized with respect to molecular weight, isoelectric point, absorption spectrum and amino acid composition. The alpha and beta subunits of each of these proteins were also purified to homogeneity and characterized in the same manner. The tetrapyrrole chromophore content was determined for each of the proteins and subunits. The alpha subunit of phycoerythrocyanin carries a novel phycobiliviolin-like chromophore. This chromophore has not previously been detected in cyanobacterial biliproteins, but has been noted as a prosthetic group of a cryptophytan phycocyanin. Sedimentation equilibrium studies show that at pH 7.0, at protein concentrations of 0.2-0.6 mg/ml, allophycocyanin, C-phycocyanin and phycoerythrocyanin, each exists as a trimeric aggregate, (alphabeta)3, of molecular weight of approximately 105000. Structrual studies of microcrystals of these three biliproteins by electron microscopy and X-ray diffraction reveal a common plan for the construction of higher assembly forms. The major building block appears to be the trimer (alphabeta)3. It is proposed that this is a disc-like structure about 3.0 X 12.0 nm. The individual alpha or beta subunits are roughly spherical, 3 nm in diameter. Allophycocyanin trimers stack to form bundles of rods which form long needles. Both phycocyanin and phycoerythrocyanin form double discs (alphabeta)6 which are visible as ring-shaped structures by electron microscopy. The mode of assembly of the biliprotein structures in the phycobilisome is, as yet, unknown.

journal_name

Arch Microbiol

journal_title

Archives of microbiology

authors

Bryant DA,Glazer AN,Eiserling FA

doi

10.1007/BF00416970

subject

Has Abstract

pub_date

1976-10-11 00:00:00

pages

61-75

issue

eissn

0302-8933

issn

1432-072X

journal_volume

110

pub_type

杂志文章

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Characterization and structural properties of the major biliproteins of Anabaena sp.