1nkz
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(New page: 200px<br /><applet load="1nkz" size="450" color="white" frame="true" align="right" spinBox="true" caption="1nkz, resolution 2.00Å" /> '''Crystal structure of...)
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Revision as of 20:13, 20 November 2007
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Crystal structure of LH2 B800-850 from Rps. acidophila at 2.0 Angstrom resolution
Overview
The structure at 100K of integral membrane light-harvesting complex II, (LH2) from Rhodopseudomonas acidophila strain 10050 has been refined to, 2.0A resolution. The electron density has been significantly improved, compared to the 2.5A resolution map, by high resolution data, cryo-cooling, and translation, libration, screw (TLS) refinement. The electron density, reveals a second carotenoid molecule, the last five C-terminal residues of, the alpha-chain and a carboxy modified alpha-Met1 which forms the ligand, of the B800 bacteriochlorophyll. TLS refinement has enabled the, characterisation of displacements between molecules in the complex. B850, bacteriochlorophyll molecules are arranged in a ring of 18 pigments, composed of nine approximate dimers. These pigments are strongly coupled, and at their equilibrium positions the excited state dipole interaction, energies, within and between dimers, are approximately 370cm(-1) and, 280cm(-1), respectively. This difference in coupling energy is similar in, magnitude to changes in interaction energies arising from the pigment, displacements described by TLS tensors. The displacements appear to be, non-random in nature and appear to be designed to optimise the modulation, of pigment energy interactions. This is the first time that LH2 pigment, displacements have been quantified experimentally. The calculated energy, changes indicate that there may be significant contributions to, inter-pigment energy interactions from molecular displacements and these, may be of importance to photosynthetic energy transfer.
About this Structure
1NKZ is a Protein complex structure of sequences from Rhodoblastus acidophilus with RG1, BOG, BCL and BEN as ligands. Full crystallographic information is available from OCA.
Reference
The structure and thermal motion of the B800-850 LH2 complex from Rps.acidophila at 2.0A resolution and 100K: new structural features and functionally relevant motions., Papiz MZ, Prince SM, Howard T, Cogdell RJ, Isaacs NW, J Mol Biol. 2003 Mar 7;326(5):1523-38. PMID:12595263
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