Chromatographic separation of photosystems I and II from the thylakoid membrane isolated from a thermophilic blue-green alga

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Abstract
The thylakoid membrane of a thermophilic blue-green alga, Synechococcus sp., was separated into four chlorophyll-containing fractions by a single chromatographic manipulation with a diethylaminoethyl-cellulose column after digitonin treatment. Photosystems I and II, or chlorophyll a forms, were unevenly distributed among the four fractions, which were designated F-1, F-2, F-3 and F-4 in the order of elution from the column. F-1 has a simple composition of the chlorophyll a form and totally lacks photochemical activity. This fraction may be an antenna chlorophyll a-protein in the blue-green alga. F-2 is rich in shorter wavelength chlorophyll a forms and shows the three-banded fluorescence emission spectrum characteristic of photosystem II at liquid nitrogen temperature. This fraction is highly active in 2,6-dichloroindophenol photoreduction and contains one photooxidizable cytochrome b559 per 50–100 chlorophyll a, whereas the P-700 content is as low as one P-700 per 2,000 chlorophyll a. Thus, F-2 represents photosystem II in a highly purified state. F-3 is rich in photosystem I, since this fraction is inactive in 2,6-dichloroindophenol photoreduction, and contains one P-700 per 200 chlorophyll a and smaller amounts of cytochrome b559. Longer wavelength chlorophyll a forms are abundant and a peak at 730 nm is the most prominent in the low-temperature fluorescence spectrum in this fraction. F-4, which consists of larger membrane fragments shows spectral and photochemical features similar to those of F-3.