View source for 1dv6

[[Image:1dv6.gif|left|200px]]<br /><applet load="1dv6" size="350" color="white" frame="true" align="right" spinBox="true" 
caption="1dv6, resolution 2.50&Aring;" />
'''PHOTOSYNTHETIC REACTION CENTER FROM RHODOBACTER SPHAEROIDES IN THE CHARGE-NEUTRAL DQAQB STATE WITH THE PROTON TRANSFER INHIBITOR ZN2+'''<br />

==Overview==
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.

==About this Structure==
1DV6 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Rhodobacter_sphaeroides Rhodobacter sphaeroides] with <scene name='pdbligand=FE2:'>FE2</scene>, <scene name='pdbligand=ZN:'>ZN</scene>, <scene name='pdbligand=CL:'>CL</scene>, <scene name='pdbligand=BCL:'>BCL</scene>, <scene name='pdbligand=BPH:'>BPH</scene>, <scene name='pdbligand=U10:'>U10</scene> and <scene name='pdbligand=LDA:'>LDA</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1DV6 OCA]. 

==Reference==
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:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=10677497 10677497]
[[Category: Protein complex]]
[[Category: Rhodobacter sphaeroides]]
[[Category: Abresch, E C.]]
[[Category: Axelrod, H L.]]
[[Category: Feher, G.]]
[[Category: Okamura, M Y.]]
[[Category: Paddock, M L.]]
[[Category: BCL]]
[[Category: BPH]]
[[Category: CL]]
[[Category: FE2]]
[[Category: LDA]]
[[Category: U10]]
[[Category: ZN]]
[[Category: bacterial photosynthesis]]
[[Category: cation binding]]
[[Category: integral membrane protein]]
[[Category: metal ion binding]]
[[Category: proton transfer]]
[[Category: rhodobacter sphaeroides]]
[[Category: x-ray crystallography]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:20:46 2008''