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'Reaction Center' in keywords Facet   section ZfN Section C:Volume 046  [X]
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1991 (2)
1Author    I. Agalidis, E. Rivasb, F. Reiss-HussonaRequires cookie*
 Title    Characterization of Reaction Center-B875 Complex of Rhodocyclus gelatinosus: Q B Site Properties Derived from Reconstitution Experiments  
 Abstract    Purified reaction center-B875 pigment-protein complex isolated from Rc. gelatinosus (I. Agalidis, E. Rivas, and F. Reiss-Husson, Photosynth. Res. 23, 2 4 9 -2 5 5 (1990)) was further characterized. In the chromatophores, the quinone content was shown to be 6 menaquinones 8 and 16 ubiquinones 8 per reaction center, indicating that the pool contained both quinone types. Besides the primary (M K S) and secondary (U Q X) electron acceptors o f the reaction cen­ ter, the com plex contains residual quinones from the membrane pool (about 3 M K X and 5 U Q 8) probably associated with the phospholipids. Apparent particle weight o f the complex including bound detergent was 520 ± 46 kDa. The secondary quinone Q B was partially removed from the RC by treatment with 2 -3 % octaethyleneglycol dodecyl ether and 3 —4 m M orthophenanthroline. Reconstitution experi­ ments showed that U Q 6, U Q 9 and U Q ,0 could replace Q B but that M K S and M K , could not. It was concluded that Q B site has a clear specificity towards ubiquinone binding. 
  Reference    Z. Naturforsch. 46c, 99—105 (1991); received October 10/November 26 1990 
  Published    1991 
  Keywords    Purple Bacteria, Reaction Center, Secondary Electron Acceptor, Quinones 
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 TEI-XML for    default:Reihe_C/46/ZNC-1991-46c-0099.pdf 
 Identifier    ZNC-1991-46c-0099 
 Volume    46 
2Author    Bengt Svensson, Imre Vass, Stenbjörn StyringRequires cookie*
 Title    Sequence Analysis of the D 1 and D 2 Reaction Center Proteins of Photosystem II  
 Abstract    A com pilation o f 38 sequences for the D1 and 15 sequences for the D 2 reaction center pro­ teins o f photosystem II is presented. The sequences have been compared and a similarity index that takes into account the degree o f conservation and the quality o f the changes in each posi­ tion has been calculated. The similarity index is used to identify and describe functionally im­ portant domains in the D 1 /D 2 heterodimer. Comparative hydropathy plot are presented for the aminoacid sidechains that constitute the binding domain o f the tyrosine radicals, Tyrz and TyrD, in photosystem II. The structure around Tyrz is more hydrophilic than the structure around TyrD. The hydrophilic residues are clustered in the part o f the binding pocket for Tyrz that is turned towards the lumenal side o f the thylakoid membrane. M ost prominent is the presence o f two conserved carboxylic am inoacids, D l-A sp 170 and D l-G lu 189. Their respec­ tive carboxyl-groups com e close in space and are proposed to constitute a metal binding site together with D l-G ln 165. The distance between the proposed metal binding site and the cen­ ter o f the ring o f Tyrz is approximately 7Ä . The cavity that constitutes the binding site for TyrD is com posed o f residues from the D 2 protein. Its character is more hydrophobic than the Tyrz site and the environment around TyrD lacks the cluster o f putative metal binding side­ chains. 
  Reference    Z. Naturforsch. 46c, 765 (1991); received March 13 1991 
  Published    1991 
  Keywords    Photosystem II, D1 Protein, D 2 Protein, Tyrosine, M anganese, Reaction Center 
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 TEI-XML for    default:Reihe_C/46/ZNC-1991-46c-0765.pdf 
 Identifier    ZNC-1991-46c-0765 
 Volume    46