Bacteriochlorin-protein interactions in native B800-B850, B800 deficient and B800-Bchla(p)-reconstituted complexes from Rhodopseudomonas acidophila, strain 10050.

Recently, a method which allows the selective release and removal of the 800 nm absorbing bacteriochlorophyll a (B800) molecules from the LH2 complex of Rhodopseudomonas acidophila strain 10050 has been described [Fraser, N.J. (1999) Ph.D. Thesis, University of Glasgow, UK]. This procedure also allows the reconstitution of empty binding sites with the native pigment Bchla(p), esterified with phytol. We have investigated the bacteriochlorophylla-protein interactions in native, B800 deficient (or B850) and in B8110-bacteriochlorophylla(p)-reconstituted LH2 complexes by resonance Raman spectroscopy. We present the first direct structural evidence which shows that the reconstituted pigments are correctly bound within their binding pockets.