1kn1
Crystal structure of allophycocyanin
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OverviewOverview
The crystal structure of allophycocyanin from red algae Porphyra yezoensis, (APC-PY) at 2.2-A resolution has been determined by the molecular, replacement method. The crystal belongs to space group R32 with cell, parameters a = b = 105.3 A, c = 189.4 A, alpha = beta = 90 degrees, gamma, = 120 degrees. After several cycles of refinement using program X-PLOR and, model building based on the electron density map, the crystallographic, R-factor converged to 19.3% (R-free factor is 26.9%) in the range of 10.0, to 2.2 A. The r.m.s. deviations of bond length and angles are 0.015 A and, 2.9 degrees, respectively. In the crystal, two APC-PY trimers associate, face to face into a hexamer. The assembly of two trimers within the, hexamer is similar to that of C-phycocyanin (C-PC) and R-phycoerythrin, (R-PE) hexamers, but the assembly tightness of the two trimers to the, hexamer is not so high as that in C-PC and R-PE hexamers. The, chromophore-protein interactions and possible pathway of energy transfer, were discussed. Phycocyanobilin 1alpha84 of APC-PY forms 5 hydrogen bonds, with 3 residues in subunit 2beta of another monomer. In R-PE and C-PC, chromophore 1alpha84 only forms 1 hydrogen bond with 2beta77 residue in, subunit 2beta. This result may support and explain great spectrum, difference exists between APC trimer and monomer.
About this StructureAbout this Structure
1KN1 is a Protein complex structure of sequences from Porphyra yezoensis with BLA and CYC as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of allophycocyanin from red algae Porphyra yezoensis at 2.2-A resolution., Liu JY, Jiang T, Zhang JP, Liang DC, J Biol Chem. 1999 Jun 11;274(24):16945-52. PMID:10358042
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