ISOLATION and SPECTROSCOPIC CHARACTERIZATION OF THE B875 ANTENNA COMPLEX OF A MUTANT OF Rhodopseudomonas sphaeroides

Abstract— We describe a procedure of purification of the B875 antenna complex isolated from the 3P17 mutant strain of Rhodopseudomonas sphaeroides, enriched in B875. The integrity of this isolated complex, as well as a very low content of residual B800-850 antenna, was suggested from low temperature absorption and resonance Raman spectra. Time resolved experiments were also carried out. The important result is the identity of the fluorescence lifetime of the B875 isolated complex (0.64 ± 0.03 ns) with that of the B875 antenna in vivo (0.63 ns), in the membrane of the C71 reaction center-less mutant of Rhodopseudomonas sphaeroides, measured in our previous study.
Our data suggest that the interactions between the bacteriochlorophylls of the complex, as well as the constraints imposed by their protein environment are not much changed from the in vivo state.