Biochemical and immunochemical investigations on the light-harvesting system of the cryptophyte Rhodomonas sp.: Evidence for a photosystem I specificantenna

Thylakoid membranes of the cryptophyte Rhodomonos sp. were solubilized with the mild detergent dodecyl-beta-mal-toside and subjected to sucrose densit y gradient centrifugation. The resulting gradients showed six pigment-beari ng bands which were characterized further by means of absorption and fluore scence emission (77 K) spectroscopy, polyacrylamide gel electrophoresis and Western immunoblotting. Two of the bands showed characteristics of light-h arvesting complexes, other bands could be attributed to photosystem II and photosystem I. Up to 10 different light-harvesting proteins could be identi fied, some of which are specific for photosystem I, others for photosystem II. The polypeptides of the light-harvesting complex of photosystem II show a higher chlorophyll c/a ratio than the antenna proteins of photosystem I. As in vascular plants, they represent the bulk of the membrane-intrinsic l ight-harvesting proteins.