title: Allophycocyanin B (lambdamax 671, 618 nm): a new cyanobacterial phycobiliprotein.
abstract: A hitherto undescribed red fluorescent phycobiliprotein (maximum emission at congruent to 680 nm), characterized by long wavelength absorption maxima in the visible region at 671 nm (xi = 172000 M(-1).cm(-1) per monomer of mol. wt. 30600)and 618 nm, has been purified to homogeneity from unicellular cyanobacterium, Synechococcus sp., and from a filamentous cyanobacterium, Anabaena variabilis.  The name allophycocyanin B has been proposed for the new protein.  A. variabilis allophycocyanin B is characterized by a native molecular weight of 89000 p 5000 (in 0.05 M phosphate at pH 7.2), an isoelectric point of 5.09, and a subunit molecular weight, based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, of 15300.  The protein contains one phycocyanobilin chromophore per subunit.  In common with allophycocyanin from the same organism, allophycocyanin B does not contain either histidine or tryptophan.  In other respects, the amino acid compositions of the two proteins are significantly different.  Synechococcus sp. (Anacytis nidulans) allophycocyanin B gives two components of 16000 and 17000 mol. wt., of equal staining intensity, on sodium dodecyl sulfate-polyacrylamide gel electrophoresis.  Allophycocyanin B from both organisms cross-react with rabbit antisera directed against either Synechococcus sp. or Anabaena sp. allophycocyanin, but not with antisera against the phycocyanins of the same organisms.  It is suggested that allophycocyanin B occupoes a position between allophycocyanin and chlorophyll a in the energy transfer path from the accessory pigments to species of chlorophyll a with absorption maxima at lambda greater than 670 nm.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002734:Chlorophyll / Q000032:analysis; D002848:Chromatography, DEAE-Cellulose; D003429:Cross Reactions; D000458:Cyanobacteria / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D005779:Immunodiffusion; D007526:Isoelectric Point; D008970:Molecular Weight; D010798:Phycocyanin / Q000032:analysis* / Q000302:isolation & purification; D010860:Pigments, Biological / Q000032:analysis*; D011817:Rabbits / Q000276:immunology; D012967:Sodium Dodecyl Sulfate; D013053:Spectrophotometry
chemical_list: D000596:Amino Acids; D010860:Pigments, Biological; D010798:Phycocyanin; D002734:Chlorophyll; D012967:Sodium Dodecyl Sulfate