J. Biol. Chem., Vol. 261, Issue 7, 3020-3024, 03, 1986
Structure of the B880 holochrome of Rhodospirillum rubrum as studied by the radiation inactivation method
R Picorel, A L'Ecuyer, M Potier and G Gingras
Chromatophores from photoreaction centerless strain F24 of Rhodospirillum
rubrum were subjected to different doses of gamma radiation. Target theory
was applied to the induced decay of the B880 holochrome pigments as
analyzed by absorption spectroscopy of the membranes and of organic solvent
extracts. Destruction of bacteriochlorophyll is associated with a target
size of 7 kDa. This indicates that each one of the two different 6-kDa
holochrome polypeptides binds one molecule of this pigment. The target size
of spirilloxanthin, 12 kDa, suggests that both polypeptides contribute to
the binding site of this carotenoid. The 880 nm absorption band and the
oxidation-induced 1225 nm band have a target size of 14 kDA. Therefore,
these bands are due to interaction between two bacteriochlorophyll
molecules, each one of which resides on a different polypeptide. This
14-kDa complex decays into a bacteriochlorophyll monomer associated with a
target size of 7 kDa. The absolute absorption spectra of the protein-bound
bacteriochlorophyll pair and monomer are presented.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?