Download MendeleyMolecular structure of a high potential cytochrome c2 isolated from Rhodopila globiformis.
Benning, M.M., Meyer, T.E., Holden, H.M.(1996) Arch Biochem Biophys 333: 338-348
- PubMed: 8809072
- DOI: https://doi.org/10.1006/abbi.1996.0400
- Primary Citation of Related Structures:
1HRO - PubMed Abstract:
Unlike their mitochondrial counterparts, the c-type cytochromes typically isolated from photosynthetic nonsulfur purple bacteria display a wide range of oxidation-reduction potentials. Here we describe the X-ray crystallographic analysis of the cytochrome c2 isolated from Rhodopila globiformis. This particular c-type cytochrome was selected for study because of its anomalously high redox potential of +450 mV. Crystals employed in the investigation belonged to the space group I4(1) with unit cell dimensions of a = b = 79.2 A, c = 75.2 A, and two molecules in the asymmetric unit. The structure was solved by the techniques of multiple isomorphous replacement with two heavy-atom derivatives and electron density modification procedures. Least-squares refinement of the model reduced the R-factor to 18.7% for all measured X-ray data from 30.0 to 2.2 A. The overall structural motif of the protein is composed of five alpha-helices, one type I turn, and six type II turns. As in other cytochromes c, there are two conserved water molecules located in the heme-binding pocket. Overall, the three-dimensional structure of the R. globiformis molecule is more similar to the eukaryotic c-type cytochromes than to other bacterial proteins.
Organizational Affiliation:
Institute for Enzyme Research, Graduate School, University of Wisconsin, Madison 53705, USA.
