ISSN:
1573-5079
Keywords:
BChl c aggregates
;
cross-linking
;
green bacteria
;
light-harvesting antenna
;
pigment organization
;
ultrastructure
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Isolated chlorosomes, treated with the detergent lithium dodecyl sulfate (LDS), can be separated into two green fractions by agarose gel electrophoresis. One fraction contains chlorosomes with a full complement of proteins and antenna BChl c absorbing at 740 nm, but with a more spherical form than the normal ellipsoid shape observed in control chlorosomes. The second fraction was completely devoid of proteins but had a similar absorption spectrum. Electron micrographs of the protein-free fraction indicated the presence of stain-excluding spheres with overall dimensions resembling those of intact chlorosomes (40–100 nm). These spheres are probably micelles of BChl c liberated from the chlorosomes during the detergent treatment, since similar structures could be produced when purified BChl c, dissolved in 1-hexanol, was dispersed in buffer, producing an aggregate absorbing at 742 nm. These results suggest that the chlorosome proteins are not required to produce an arrangement of BChl c chromophores which gives rise to a 740 nm absorption peak resembling that of intact chlorosomes. It seems probable, however, that proteins have a role in determining the overall shape of the chlorosome. Treatment with cross-linking reagents did not prevent the detergent-induced changes in chlorosome morphology.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00016558
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