1kn1: Difference between revisions

[[Image:1kn1.gif|left|200px]]<br /><applet load="1kn1" size="350" color="white" frame="true" align="right" spinBox="true"  

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.

1KN1 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Porphyra_yezoensis Porphyra yezoensis] with <scene name='pdbligand=BLA:'>BLA</scene> and <scene name='pdbligand=CYC:'>CYC</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1KN1 OCA].  

[[Category: Chang, W R.]]

[[Category: Liang, D C.]]

[[Category: Liu, J Y.]]

[[Category: Zhang, J P.]]

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