The preparation and characterisation of native photoreceptor units from the thylakoids of Rhodopseudomonas viridis

Publisher Website
Google Scholar
Abstract
The photosynthetic membranes of R. viridis consist of a regular array of structural units. Each unit is composed of a central core (thought to contain the reaction center complex) surrounded by a subdivided ring of protein (of likely antennae function). These individual units can be dissociated from the membranes using a variety of detergent treatments. The absorption spectrum, used as a criterion of a native state, is retained. All of the 7 major polypeptides, the 4 reaction center polypeptides (cytochrome, H, M and L chain) and the 3 light-harvesting polypeptides (B1015-.alpha., .beta. and .gamma.) are present. EM of the units shows a similar structure to the units within the membrane. Surface-specific iodination of both membranes and units labels predominantly polypeptides H, B1015-.alpha. and .gamma.. M and L are weakly labeled. B1015-.beta. is labeled in the isolated units. This, with other evidence, supports an allocation of light-harvesting polypeptides to the outer ring. Further solubilization of these units separates the reaction center (as a native complex containing all 4 polypeptides) from the light-harvesting polypeptides. The light-harvesting polypeptides are obtained in a form containing all 3 polypeptides and bound pigment; the peak at 1015 nm corresponding to native bacteriochlorophyll b is lost.

This publication has 10 references indexed in Scilit: