1ds8

PHOTOSYNTHETIC REACTION CENTER FROM RHODOBACTER SPHAEROIDES IN THE CHARGE-NEUTRAL DQAQB STATE WITH THE PROTON TRANSFER INHIBITOR CD2+

spinqualitylabelsall models 1ds8, resolution 2.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1ds8 is a 6 chain structure with sequence from Cereibacter sphaeroides. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.5Å Ligands: BPH, CD, CL, FE2, LDA, U10 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function RCEL_CERSP The reaction center is a membrane-bound complex that mediates the initial photochemical event in the electron transfer process of photosynthesis. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The reaction center (RC) from Rhodobacter sphaeroides couples light-driven electron transfer to protonation of a bound quinone acceptor molecule, Q(B), within the RC. The binding of Cd(2+) or Zn(2+) has been previously shown to inhibit the rate of reduction and protonation of Q(B). We report here on the metal binding site, determined by x-ray diffraction at 2.5-A resolution, obtained from RC crystals that were soaked in the presence of the metal. The structures were refined to R factors of 23% and 24% for the Cd(2+) and Zn(2+) complexes, respectively. Both metals bind to the same location, coordinating to Asp-H124, His-H126, and His-H128. The rate of electron transfer from Q(A)(-) to Q(B) was measured in the Cd(2+)-soaked crystal and found to be the same as in solution in the presence of Cd(2+). In addition to the changes in the kinetics, a structural effect of Cd(2+) on Glu-H173 was observed. This residue was well resolved in the x-ray structure-i.e., ordered-with Cd(2+) bound to the RC, in contrast to its disordered state in the absence of Cd(2+), which suggests that the mobility of Glu-H173 plays an important role in the rate of reduction of Q(B). The position of the Cd(2+) and Zn(2+) localizes the proton entry into the RC near Asp-H124, His-H126, and His-H128. Based on the location of the metal, likely pathways of proton transfer from the aqueous surface to Q(B) are proposed. Determination of the binding sites of the proton transfer inhibitors Cd2+ and Zn2+ in bacterial reaction centers.,Axelrod HL, Abresch EC, Paddock ML, Okamura MY, Feher G Proc Natl Acad Sci U S A. 2000 Feb 15;97(4):1542-7. PMID:10677497 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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