The Photochemical Change in
Photosynthetic Reaction Center of Purple Bacterium with Pheophytin Substitution
ZENG Xiao-Hua, XU Chun-He*, WU Yong-Qiang, LIU
Xian-Nian1 and SHEN Yun-Gang
（ Shanghai Institute of Plant Physiology, the Chinese Academy of
Science, Shanghai 200032, China;
1Institute of Laser chemistry, Fudan University, Shanghai
200433, China )
Abstract The reaction centers are
isolated from chromatophores of Rhodobacter sphaeroides 601 by
detergent LDAO, and purified by chromatography on a DEAE-52 cellulose column.
In the presence of acetone and an access of free pheophytins (Phes),
bacteriopheophytins (Bphes) in reaction centers are replaced by pheophytins at
sites HA and HB when incubated under high temperature.
The substituting amounts are about 50% and 71% Bphes in reaction centers with
incubation of fifteen and sixty minutes respectively. In the absorption spectra
of reaction centers containing Phes (Phe RC), the QX（537 nm）and QY（758 nm）bands of Bphe disappeared,
three distinct bands assigned to the QX（509/542 nm）and QY（674 nm）bands of phe appeared.
Compared to reaction centers in control, the photochemical activities of Phe
RCs, with incubating time of fifteen and sixty minutes, drop to 78％ and 71% of that in control
respectively。
Key Words Photosynthetic reaction center； purple bacteria； pheophytin replacement； photochemical activity
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