Reaction Center of a Thermophilic Cyanobacterium

THE SINGLE SUBUNIT P-700 REACTION CENTER OF A THERMOPHILIC CYANOBACTERIUM 

In an earlier communication (Nechushtai et al. 1983) we reported on the purification of the photosystem I reaction center from the thermophilic cyanobacterium Mastigocladus laminosus. The subunit composition and the photochemical properties of this reaction center were compared with those of photosystem I reaction centers from green algae and higher plants. Immunological crossreactivity between subunits 1 as well as between subunits II from these different sources was indicated and its evolutional significance was discussed. 

We describe here the isolation and characterization of subunit I of Mastigocladus laminosus as a fully active photosystem I reaction center by its own. 

Cells were grown at 30 C as described earlier (Binder and Bachofen, 1979). The membrane preparation as well as the isolation of the multiple subunit reaction center was done according to Nechushtai et al. (1983). SDS-PAGE was done as described by Wiemken et al. (1981). If not stated otherwise the samples for the SDS-PAGE were treated with 2% SDS for 20 min at 60 (SDS to chlorophyll ratio 20 1). Protein determination was done according to Peterson (1977 and chlorophyll determination aft r extraction with 80% acetone using an extinction coefficient of 80.04 mM cm at 663 nm. 

FIGURE SDS-PAGE Increasing SDS to protein ratios in the sample preparation. 

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