β Scribed by Yuichiro Takahashi; Sakae Katoh
No coin nor oath required. For personal study only.
Treatment of lyophilized thylakoid membranes of the thermophflic cyanobacterium Synechococcus sp. with n-heptane for 6 h resulted in marked changes in the pattern of photosystem I reaction center complexes resolved by sodium dodecylsulfatepolyacrylamidc gel electrophoresis. CPI-a, which consists of two large subunits and three small subunits, was a major chlorophyll-containing band resolved from the lyophilized thylakoid membranes, whereas the heptane-extracted membranes produced mainly CPI-e which totally lacks the small subunits. Electron transport from the primary donor PT00 to the secondary accepter P430 was not affected by the heptane-extraction of the membranes. The heptane-treatment removed 97% of E-carotene present in the membranes, whereas all chlorophyll a, a major part of xanthophylls, more than a half of phylloquinone and one third of plastoquinone remained unextracted. The data suggest that #-carotene has an important structural effect to stabilize the subunit organization of photosystem I reaction center complexes but is not essential for the early photochemical events of photosystem I.
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Several cDNA clones encoding the complete subunit II and III precursor polypeptides of the photosystem I reaction center were isolated from two spinach lambda gt1 1 expression libraries by immunoscreening and homologous hybridization. The identity of the recombinant cDNAs was verified by an N-termin
## Abstract Aqueous extracts of the contents of the duodenum of chickens have been found on many occasions to be bacteriostatic. On some occasions such extracts were stimulatory. Stimulatory extracts were rendered inhibitory by removing the substances precipitated by alcohol. These and other proper