Photosynthetic unit size, carotenoids, and chlorophyll—protein composition of Prochloron sp., a prokaryotic green alga
- 1 May 1978
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 75 (5), 2301-2305
- https://doi.org/10.1073/pnas.75.5.2301
Abstract
Six samples of the prokaryotic, unicellular algae Prochloron sp., which occur in association with didemnid ascidians, were collected from various localities in the tropical Pacific Ocean, and their pigments and chlorophyll-protein complexes were identified and characterized. No phycobilin pigments were detected in any of the species. Chlorophylls a and b were present in ratios of a/b = 4.4-6.9. The major carotenoids were .beta.-carotene (70%) and zeaxanthin (20%). Minor carotenoids of one isolate were identified as echinenone, cryptoxanthin, isocryptoxanthin, mutachrome and trihydroxy-.beta.-carotene; no .epsilon.-ring carotenoids were found in any sample. Except for the absence of glycosidic carotenoids, the overall pigment composition is typical of cyanobacteria. A chlorophyll a/b-protein complex was present in Prochloron; it was electrophoretically and spectrally indistinguishable from the light-harvesting chlorophyll a/b-protein of higher plants and green algae. It accounted for 26% (compared to .apprx. 50% in green plants) of the total chlorophyll; 17% was associated with a P700-chlorophyll a-protein. The photosynthetic unit size of 240 .+-. 10 chlorophylls per P700 in Prochloron was about half that of eukaryotic green plants. A model is proposed for the in vivo organization of chlorophyll in Prochloron.This publication has 8 references indexed in Scilit:
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