Biochemistry I   Spring & Fall Terms

Photosynthetic Reaction Center (PSRC)

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  Distances (Å):
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  Cofactors and water.
  Cardiolipin.
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  Cofactors and water.
  Cardiolipin.

Two views of cardiolipin:
  1. The lipid is Spacefill.
  2. Protein surface contacts are Spacefill.

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Photosynthetic Reaction Center from Rhodopseudomonas sphaeroides
The photosynthetic reaction center (PSRC)* is shown as Cartoons, oriented with the cytoplasmic domain at bottom. The complex is made up of three protein subunits and 10 cofactors. Together, they function to pump electrons across the cytoplasmic membrane of photosynthetic bacteria. The L (magenta) and M (green) subunits have five transmembrane a-helices; the H (purple) subunit has one transmembrane a-helix.
The cofactors are shown spacefill and colored as follows: four bacterial chlorophylls, redorange; two bacteriopheophytins, cyan; ubiquione, yellow; spheroidenone, pink; one non-heme iron, orange; and waters as small red balls. In addition, the membrane lipid, cardiolipin, is shown spacefill, colored CPK (Fig. 1B).

Two views of the bound cardiolipin (Figs. 2A and 2B):
1. The lipid is Spacefill, colored CPK. Protein residues within 10 Å are shown as Sticks.
2. The protein surface that contacts the lipid is Spacefill. The lipid is shown as Sticks with a dot surface. The coloring is "Temperature".

*The structure of the photosynthetic reaction center from Rhodopseudomonas sphaeroides is described by McAuley et al. (1999) PNAS 96 14706-14711. The coordinate file is 1QOV.pdb. (References to Figs. above are to those of McAuley et al.)

Four more membrane protein structures:
 Bacteriorhodopsin       K+-Channel       Maltoporin       a-Hemolysin       Reaction Center

Back to the Protein Structure List.

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8.21.04