Fluorescence Emission Spectroscopy of Single Light-Harvesting Complex from Green Filamentous Photosynthetic Bacteria

摘要

The fluorescence emission properties of supramolecular light-harvesting complexes (= chlorosomes) from a green filamentous photosynthetic bacterium (Chloroflexus aurantiacus) on a quartz plate were studied for the first time at the single-unit level with a total internal reflection fluorescence microscope. Atomic force microscope observation evidenced that most chlorosomes were independently situated on the quartz plate. All the fluorescence bands from bacteriochlorophyll-c aggregates of a single chlorosome had a similar peak position and also a similar bandwidth. The conservative spectroscopic properties of each Chloroflexus chlorosome indicate that the presence of stereoisomers at the 3~1-position of bacteriochlorophyll-c molecules (3~1-R/S = 2/1) does not provide any heterogeneity of chlorosomal pigment organization among Chloroflexus chlorosomes.