2bhw: Difference between revisions

The plant light-harvesting complex of photosystem II (LHC-II) collects and, transmits solar energy for photosynthesis in chloroplast membranes and has, essential roles in regulation of photosynthesis and in photoprotection., The 2.5 A structure of pea LHC-II determined by X-ray crystallography of, stacked two-dimensional crystals shows how membranes interact to form, chloroplast grana, and reveals the mutual arrangement of 42 chlorophylls a, and b, 12 carotenoids and six lipids in the LHC-II trimer. Spectral, assignment of individual chlorophylls indicates the flow of energy in the, complex and the mechanism of photoprotection in two close chlorophyll, a-lutein pairs. We propose a simple mechanism for the xanthophyll-related, slow component of nonphotochemical quenching in LHC-II, by which excess, energy is transferred to a zeaxanthin replacing violaxanthin in its, binding site, and dissipated as heat. Our structure shows the complex in a, quenched state, which may be relevant for the rapid, pH-induced component, of nonphotochemical quenching.

2BHW is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Pisum_sativum Pisum sativum] with LUX, NEX, XAT, CLA, CHL, LHG and DGD as [http://en.wikipedia.org/wiki/ligands ligands]. Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2BHW OCA].  

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