1dop

Theoretical Model: The protein structure described on this page was determined theoretically, and hence should be interpreted with caution.

THEORETICAL MODEL OF PHOTOSYSTEM II REACTION CENTER (CORE)

spinqualitylabelsall models 1dop Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights For a guided tour on the structure components use FirstGlance. Resources: FirstGlance, PDBsum, ProSAT Publication Abstract from PubMed For a detailed understanding of the function of photosystem II (PSII), a molecular structure is needed. The crystal structure has not yet been determined, but the PSII reaction center proteins D1 and D2 show homology with the L and M subunits of the photosynthetic reaction center from purple bacteria. We have modeled important parts of the D1 and D2 proteins on the basis of the crystallographic structure of the reaction center from Rhodopseudomonas viridis. The model contains the central core of the PSII reaction center, including the protein regions for the transmembrane helices B, C, D, and E and loops B-C and C-D connecting the helices. In the model, four chlorophylls, two pheophytins, and the nonheme Fe2+ ion are included. We have applied techniques from computational chemistry that incorporate statistical data on side-chain rotameric states from known protein structure and that describe interactions within the model using an empirical potential energy function. The conformation of chlorophyll pigments in the model was optimized by using exciton interaction calculations in combination with potential energy calculations to find a solution that agrees with experimentally determined exciton interaction energies. The model is analyzed and compared with experimental results for the regions of P680, the redox active pheophytin, the acceptor side Fe2+, and the tyrosyl radicals TyrD and TyrZ. P680 is proposed to be a weakly coupled chlorophyll a pair which makes three hydrogen bonds with residues on the D1 and D2 proteins. In the model the redox-active pheophytin is hydrogen bonded to D1-Glu130 and possibly also to D1-Tyr126 and D1-Tyr147. TyrD is hydrogen bonded to D2-His190 and also interacts with D2-Gln165. TyrZ is bound in a hydrophilic environment which is partially constituted by D1-Gln165, D1-Asp170, D1-Glu189, and D1-His190. These polar residues are most likely involved in proton transfer from oxidized TyrZ or in metal binding. A model for the photosystem II reaction center core including the structure of the primary donor P680.,Svensson B, Etchebest C, Tuffery P, van Kan P, Smith J, Styring S Biochemistry. 1996 Nov 19;35(46):14486-502. PMID:8931545 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

Proteopedia Page Contributors and Editors (what is this?)

OCA