Highly purified photosynthetic reaction center (PscA/cytochrome c551)2 complex of the green sulfur bacterium Chlorobium limicola

Biochemistry. 1995 Oct 10;34(40):13091-7. doi: 10.1021/bi00040a021.

Abstract

The photosynthetic reaction center (RC) complex that forms a homodimer of core and cytochrome c subunits was isolated from Chlorobium limicola f. thiosulfatophilum, strain Larsen. The complex showed only two subunit bands at 68 (PscA core) and 21 kDa (cytochrome c551) on SDS-PAGE analysis, indicating the complete deletion of the light-harvesting bacteriochlorophyll a (BChl a) protein as well as the iron-sulfur protein. It contained 27 +/- 3 molecules of BChl a, 7 +/- 1 Chl-670, 3 +/- 1 carotenoids, and 1.6 +/- 0.1 c-type hemes per the primary electron donor P840. The complex showed a light-induced charge separation and recombination between P840 and the acceptor Chl-670 at 77 K as follows: P840*Chl-670-->P840+Chl-670(-)-->P840TChl-670-->P84 0 Chl-670. Pigment compositions and their function in the (PscA/cytochrome c551)2 complex were studied by absorption, circular dichroism, and fluorescence spectroscopy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteria / enzymology*
  • Bacterial Proteins*
  • Circular Dichroism
  • Cytochrome c Group / chemistry*
  • Gram-Negative Bacteria / chemistry
  • Light-Harvesting Protein Complexes
  • Molecular Weight
  • Photochemistry
  • Photosynthetic Reaction Center Complex Proteins / chemistry*
  • Photosystem I Protein Complex*
  • Spectrometry, Fluorescence
  • Spectrum Analysis

Substances

  • Bacterial Proteins
  • Cytochrome c Group
  • Light-Harvesting Protein Complexes
  • Photosynthetic Reaction Center Complex Proteins
  • Photosystem I Protein Complex
  • PscA protein, green sulfur bacteria
  • cytochrome C(551)