ISSN:
1573-5079
Keywords:
2D crystals
;
image processing
;
membrane protein structure
;
reaction centre
;
Rhodospirillum rubrum
;
transmission electron microscopy
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The minimal photounit of the photosynthetic membranes of the purple non-sulphur bacterium Rhodospirillum rubrum, comprising the reaction centre and the light-harvesting complex has been purified and crystallised in two dimensions in the presence of added phospholipids, and subsequently visualised by electron microscopy after negatively-staining. The position of the reaction centres within the light-harvesting ring has been determined at low resolution by the application of a new analysis for rotationally disordered identical units (here the reaction centres) within a two-dimensional crystalline lattice comprised of perfectly aligned unit cells (here the light-harvesting complexes). The reaction centre was found to preferentially occupy one of four orientations within the light-harvesting complex. The light-harvesting complex appears to be distorted to C4 symmetry, thus assuming a squarish shape when visualised by negative staining. A tentative structural model of the reaction centre-light-harvesting complex photounit which fits the experimental data is proposed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1005964123955
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