Selective Release, Removal, and Reconstitution of Bacteriochlorophyll <i>a</i> Molecules into the B800 Sites of LH2 Complexes from <i>Rhodopseudomonas acidophila</i> 10050

Abstract

A method is described which allows the selective release and removal of the Bchla-B800 molecules from the LH2 complex of Rhodopseudomonas acidophila 10050. This procedure also allows reconstitution of approximately 80% of the empty binding sites with native Bchla. As shown by circular dichroism spectroscopy, the overall structures of the B850-only and reconstituted complexes are not affected by the pigment-exchange procedure. The pigments reconstituted into the B800 sites can also efficiently transfer excitation energy to the Bchla-B850 molecules.