The Photoreaction Unit in Rhodopseudomonas viridis

概要

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We have examined the properties of the photoreaction unit (PRU) purified from the photosynthetic membrane of Rhodopseudomonas viridis by polyacrylamide gel electrophoresis in the presence of 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS). The absorption spectrum and the X-ray diffraction pattern of the isolated PRU were quite similar to those of the PRU in the native photosynthetic membrane. Cytochrome, the H-, M-, and L-subunits of the reaction center (RC), and the α-, β- and γ-subunits of light-harvesting chlorophyll protein (LH) were retained in the PRU. Levels of bacteriochlorophyll b and carotenoids in PRU were predominantly unchanged during the purification procedure. Gel filtration indicated a molecular weight of about 540 kDa in the presence of 0.5% CHAPS. Two high-potential hemes (Em=360 mV) and two low-potential hemes (Em=5 mV) were observed in the PRU. The molar extinction coefficient of the PRU at 1,005 nm was estimated to be 4.3 μM^<-1>・cm^<-1>. The purified PRU showed a light-induced current response between two electrodes.
日本植物生理学会の論文