1cpc
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ISOLATION, CRYSTALLIZATION, CRYSTAL STRUCTURE ANALYSIS AND REFINEMENT OF CONSTITUTIVE C-PHYCOCYANIN FROM THE CHROMATICALLY ADAPTING CYANOBACTERIUM FREMYELLA DIPLOSIPHON AT 1.66 ANGSTROMS RESOLUTION
OverviewOverview
Constitutive phycocyanin from cyanobacterium Fremyella diplosiphon, (Calothrix sp. PCC 7601) grown in green light, has been isolated and, crystallized. The crystals belong to the space group R3 with cell, constants a = b = 180.26 A, c = 61.24 A, alpha = beta = 90 degrees, gamma, = 120 degrees. The crystal structure has been determined by Patterson, search techniques using the molecular model of C-phycocyanin from the, cyanobacterium Agmenellum quadruplicatum. The asymmetric unit of the, crystal cell consists of two (alpha beta)-monomers related by a local, dyad. Three asymmetric units are arranged around a crystallographic triad, and form an (alpha beta)6-hexamer, the functional unit in the native, antenna rod. The initial structure has been refined in a cyclic manner by, energy-restrained crystallographic refinement and modelling until the, conventional crystallographic R-factor converged at 18.1% with data to a, resolution of 1.66 A. The molecular structure resembles closely the, C-phycocyanins of Mastigocladus laminosus and A. quadruplicatum. The, conformation and configuration of the alpha-84 and beta-84 chromophores is, very similar to the corresponding chromophores in the trimeric, C-phycocyanin of M. laminosus, whereas the beta-155 chromophore differs in, configuration with C(4)-Z, C(10)-Z and C(15)-Z compared to C(4)-Z, C(10)-Z, C(15)-Z,E. The stereochemistry of the beta-155 chiral centres is, C(2)-RC(3)-R and C(31)-S, respectively, whereas alpha-84 and beta-84 have, C(2)-RC(3)-R and C(31)-R. The amino acid sequences of constitutive and, inducible phycocyanin differ mainly in residues located on the surface of, the beta-subunits that mediate the inter-hexameric contacts.
About this StructureAbout this Structure
1CPC is a Protein complex structure of sequences from Fremyella diplosiphon with CYC and CH2 as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Isolation, crystallization, crystal structure analysis and refinement of constitutive C-phycocyanin from the chromatically adapting cyanobacterium Fremyella diplosiphon at 1.66 A resolution., Duerring M, Schmidt GB, Huber R, J Mol Biol. 1991 Feb 5;217(3):577-92. PMID:1899708
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