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Biofizika

[A study of the content of pigments in the light-harvesting antenna of the green bacterium from the new family Oscillochloridaceae].


PMID 15612548

Abstract

The properties of the light-harvesting superantenna of the photosynthesizing bacteria from the new family of green filamentous bacteria Oscillochloridaceae were investigated by optical spectroscopy. The antenna of Oscillochloris trichoides consists of peripheral chlorosomal and membrane subantennas. A method of isolation of Osc. trichoides chlorosomal antenna was developed using the chaothropic agent sodium thiocyanate, which simultaneously acts to stabilize chlorosomal activity. An analysis of the second derivatives of the absorption spectra of isolated chlorosomes and their acetone-methanol extracts suggested that BChl c was a predominant light-harvesting pigment in Osc. trichoides chlorosomes. Besides, it was found that, in addition to the BChl c-antenna, chlorosomes contain a minor BChl a-antenna. It was shown that the membrane BChl a-subantenna is a light-harvesting complex with absorption maxima in the near infrared region at 805 and 860 nm. Analysis of the spectral data obtained suggested that the Osc. trichoides chlorosomal antenna resembles those from Chlorobiaceae species, whereas the membrane B805-860 BChl a antenna of Osc. trichoides is close to the membrane B808-866 BChl a antenna of Chloroflexaceae species.