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Purification of Active Photosystem I-Light Harvesting Complex I from Plant Tissues
Published on: February 3, 2023
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Light-harvesting complexes of Botryococcus braunii.
Tomas E van den Berg1, Bart van Oort1, Roberta Croce2
1Biophysics of Photosynthesis, Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, 1081 HV, Amsterdam, The Netherlands.
Photosynthesis Research
|May 29, 2017
Summary
Botryococcus braunii (BB) light-harvesting complexes (LHCs) show similar pigment organization to plants, despite unique xanthophyll content. This suggests loroxanthin
Area of Science:
- Photosynthesis research
- Algal biotechnology
- Biofuel production
Background:
- Botryococcus braunii (BB) is a promising biofuel source due to high hydrocarbon content.
- Slow growth of BB hinders its biotechnological applications.
- Understanding BB's photosynthetic machinery may reveal growth limitations.
Purpose of the Study:
- To investigate the light-harvesting complexes (LHCs) of Botryococcus braunii.
- To characterize the structure, composition, and properties of BB LHCs.
- To compare BB LHCs with those of plants to understand potential growth limitations.
Main Methods:
- Purification of monomeric and trimeric LHC fractions from BB.
- Analysis of protein content and molecular weight.
- Spectroscopic analysis including circular dichroism and 77 K absorption spectra.
- Chlorophyll and xanthophyll composition analysis.
Main Results:
- Two LHC fractions (monomeric and trimeric) were purified, each containing ~25 kDa proteins.
- BB LHCs possess chlorophyll composition similar to plant LHCII but feature loroxanthin as the main xanthophyll.
- Spectra indicated minimal role of intermonomer interactions in BB LHCs, correlating with lower trimer stability possibly due to loroxanthin.
- BB LHCII properties and excitation energy transfer are comparable to plant LHCII, despite differences in chlorophyll a content and xanthophyll composition.
Conclusions:
- Botryococcus braunii light-harvesting complexes exhibit functional similarities to plant LHCII, suggesting conserved photosynthetic mechanisms.
- The unique xanthophyll composition (loroxanthin) and higher red chlorophyll a content in BB LHCII do not impede excitation energy transfer.
- Further research into BB's photosynthetic machinery may unlock strategies to overcome growth limitations for enhanced biofuel production.
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