Isolation and characteristics of small, soluble photoreactive fragments of Rhodospirillum rubrum

Comparative study of the circular dichroism spectra of reaction centers from several photosynthetic bacteria

“…Key steps in the isolation procedures involve the use of the detergent, sodium dodecyl sulfate, for solubilization and hydroxylapatite chromatography. The R. rubrum reaction centers were prepared by W. R. Smith in the laboratory of C. Sybesma (Smith et al, 1972) using sodium dodecyl sulfate and sucrose density gradient centrifugation. All samples were stored in the freeze-dried state and were resuspended in the appropriate buffer just prior to the experiments.…”

“…(BCh 1) l molecules, which_ function to transfer lightexcitation energy to the reaction center. Several purified 0~ enri.ched re-action center preparations have been made from these bacteria (Reed and Clayton, 1968;Reed, 1969;Gingras and Jol-chine, 1969; Thornber et aL~ 1969; Thornber, 1970;Smith et al, 1972}. This is in (Fowler et .ll.…”

“…Associated with the reaction centers in purple photosynthetic bacteria there are normally 40-100 antenna bacteriochlorophyll (Bchl)* 1 molecules, which function to transfer light excitation energy to the reaction center. Several purified or enriched reaction center preparations have been made from these bacteria (Reed and Clayton, 1968;Reed, 1969;Gingras and Jolchine, 1969;Thornber et al, 1969;Thornber, 1970;Smith et al, 1972). This is in contrast to green photosynthetic bacteria and higher plants from which purified reaction centers have not yet been isolated.…”

“…Whether the BPh plays an important role in the electron-transfer reactions was uncertain. Molecular weight approximations of reaction centers from R. spheroides (Feher, 1971), Rhodopseudomonas viridis (Thornber and Olson, 1971), and RhodospiriUum rubrum (Smith et al, 1972) give estimates ranging from 37,000 to 110,000.…”