| Autor: |
Montaño, Gabriel A., Bowen, Benjamin P., LaBelle, Jeffrey T., Woodbury, Neal W., Pizziconi, Vincent B., Blankenship, Robert E. |
| Zdroj: |
Biophysical Journal; October 2003, Vol. 85 Issue: 4 p2560-2565, 6p |
| Abstrakt: |
The bacteriochlorophyll (Bchl) ccontent and organization was determined for Chlorobium(Cb.) tepidumchlorosomes, the light-harvesting complexes from green photosynthetic bacteria, using fluorescence correlation spectroscopy and atomic force microscopy. Single-chlorosome fluorescence data was analyzed in terms of the correlation of the fluorescence intensity with time. Using this technique, known as fluorescence correlation spectroscopy, chlorosomes were shown to have a hydrodynamic radius (Rh) of 25±3.2nm. This technique was also used to determine the concentration of chlorosomes in a sample, and pigment extraction and quantitation was used to determine the molar concentration of Bchl cpresent. From these data, a number of ∼215,000±80,000 Bchl cper chlorosome was determined. Homogeneity of the sample was further characterized by dynamic light scattering, giving a single population of particles with a hydrodynamic radius of 26.8±3.7nm in the sample. Tapping-mode atomic force microscopy (TMAFM) was used to determine the x,y,zdimensions of chlorosomes present in the sample. The results of the TMAFM studies indicated that the average chlorosome dimensions for Cb. tepidumwas 174±8.3×91.4±7.7×10.9±2.71nm and an overall average volume 90,800nm3for the chlorosomes was determined. The data collected from these experiments as well as a model for Bchl caggregate dimensions was used to determine possible arrangements of Bchl coligomers in the chlorosomes. The results obtained in this study have significant implications on chlorosome structure and architecture, and will allow a more thorough investigation of the energetics of photosynthetic light harvesting in green bacteria. |
| Databáze: |
Supplemental Index |
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