title: Isolation, crystallization, crystal structure analysis and refinement of allophycocyanin from the cyanobacterium Spirulina platensis at 2.3 A resolution.
abstract: The phycobiliprotein allophycocyanin from the cyanobacterium Spirulina platensis has been isolated and crystallized. The crystals belong to space group P6(3)22 with cell constants a = b = 101.9 A, c = 130.6 A, alpha = beta = 90 degrees, gamma = 120 degrees, with one (alpha beta) monomer in the asymmetric unit. The three-dimensional structure of the (alpha beta) monomer was solved by multiple isomorphous replacement. The crystal structure has been refined in a cyclic manner by energy-restrained crystallographic refinement and model building. The conventional crystallographic R-factor of the final model is 19.6% with data from 8.0 to 2.3 A. The molecular structure of the subunits resembles other solved phycobiliprotein structures. In comparison to C-phycocyanin and b-phycoerythrin the major differences arise from deletions and insertions of segments involved in the protein-chromophore interactions. The stereochemistry of the alpha 84 and beta 84 chiral atoms are C(2)-R, C(3)-R and C(31)-R. The configuration (C(4)-Z, C(10)-Z and C(15)-Z) and the conformation (C(5)-anti, C(9)-syn and C(14)-anti) are equal for both chromophores.
authors.affiliation: Max-Planck-Institut für Biochemie, Martinsried, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Brejc
authors.forename: R
authors.initials: R
authors.lastname: Ficner
authors.forename: R
authors.initials: R
authors.lastname: Huber
authors.forename: S
authors.initials: S
authors.lastname: Steinbacher
mesh_terms: D000595:Amino Acid Sequence; D016384:Consensus Sequence; D018360:Crystallography, X-Ray / Q000379:methods; D000458:Cyanobacteria / Q000378:metabolism*; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010798:Phycocyanin / Q000737:chemistry* / Q000302:isolation & purification*; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid; D013816:Thermodynamics
chemical_list: D046911:Macromolecular Substances; C002497:allophycocyanin; D010798:Phycocyanin