Incorporation of amino acids into the soluble and membrane-bound proteins of chloroplasts isolated from enucleated Acetabularia

Abstract

1. 1. Chloroplasts isolated from anucleate Acetabularia fragments incorporate radioactive amino acids into their proteins: 60 % of the total radioactivity is found to be associated with the chloroplast membranes. 2. 2. The incorporation of amino acids by choroplasts isolated from algae enucleated for 1 day and for 25 days are similar. 3. 3. The amino acid composition of the Acetabularia chloroplast structural protein is remarkably similar to that of the lamellar protein of Anthirrhinum and corn chloroplasts. 4. 4. Isolated Acetabularia chloroplasts incorporate amino acids not only in their structural protein but also in other membrane-bound and soluble proteins. From comparison of the specific radioactivities it is concluded that the chloroplast DNA codes not only for the chloroplast structural protein but also for other water-insoluble proteins as well as water-soluble proteins.