Extraction and Reconstitution of Lyophilized Photosystem I Subchloroplast Fragments from Spinach Chloroplasts

Abstract

Lyophilized photosystem I subchloroplast fragments prepared from spinach chloroplasts were extracted and reconstituted. Hexane extraction eliminated 26% of the photosystem I activity without removing chlorophylls, and the reconstitution with β-carotene, an unkown lipid or chlorophyll a restored almost all the activity. Extraction with hexane-acetone (2:1, v/v) eliminated 81% of the activity with removal of 78% of the chlorophylls. In this case, reconstitution with chlorophyll a showed complete restoration of the activity, but β-carotene, the unknown lipid, and plastoquinone A caused a rather inhibitory effect. A possible explana-tion is that photosystem I reaction centers are closely surrounded by chlorophyll a; and β-carotene, the unknown lipid, and plastoquinone A function only through chlorophyll a.