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Pigment Composition of a Novel Oxygenic Photosynthetic Prokaryote Containing Chlorophyll d as the Major Chlorophyll

1997; Oxford University Press; Volume: 38; Issue: 3 Linguagem: Inglês

10.1093/oxfordjournals.pcp.a029163

1471-9053

Hideaki Miyashita, K. Adachi, Norihide Kurano, H. Ikemot, M. Chihara, Shigetoh Miyach,

Porphyrin and Phthalocyanine Chemistry

The principal pigment found in the majority of oxygenic photosynthetic organisms is known to be chlorophyll a. However, we isolated a new oxygenic photosynthetic prokaryote that contained chlorophyll d as a predominant pigment with chlorophyll a being a minor pigment. Chlorophyll d had previously been noted but its natural occurrence and function remained unclear. Cells of the new prokaryote had an absorption maximum at red region of 714–718 nm due to chlorophyll d absorption, but no characteristic absorption peak of chlorophyll a around 680 nm was observed. Chlorophyll d of the new organism was identified spectrophotometrically in several solvents and its chemical structure was confirmed by NMR and FABMS analysis. The cell also contained a chlorophyll c-like pigment, zeaxanthin and a-carotene but not chlorophyll b and β-carotene. The content of chlorophyll d accounted for more than 2% of the cell dry weight, while the content of chlorophyll a was less than 0.1%. The chlorophyll a/d ratio remained between 0.03 and 0.09 under different culture conditions. The light absorption characteristics and the high content of chlorophyll d along with the small content of chlorophyll a indicated the existence of a new light utilization mechanism involving chlorophyll d.