Abstract
Reaction centers (RCs) of the photosynthetic bacterium Rhodobacter sphaeroides R-26 were reconstituted in liposomes after release of pigments (bacteriochlorophyll α (BChlα) and bacteriopheophytin α (BPheα)) by treatment with acetone. As shown by absorption and circular dichroism spectroscopies, the reconstituted RCs had the same arrangement of pigments as the native RC and exhibited photoactivity of the special pair. The recovery yield of RCs of up to 30% was achieved by addition of 7.8-fold excess of BChlα in the acetone treatment. Furthermore BChlα was partially replaced with Zn-BChlα by addition of the pigments during the acetone treatment. About 30% and 50% of the special pair and accessory pigments can be replaced with Zn-BChlα, respectively. From this rate, an oxidation-reduction potential of 520mV (vs. the normal hydrogen electrode NHE) was derived by the simulation of the exper-imental data, which is 35mV higher than that of the native RC (484mV vs. NHE).
