Energy transfer between carotenoids and bacteriochlorophylls in light-harvesting complex II of purple bacteria

1999 ◽  
Vol 59 (3) ◽  
pp. 3293-3311 ◽  
Author(s):  
Ana Damjanović ◽  
Thorsten Ritz ◽  
Klaus Schulten
Keyword(s):  
Energy Transfer ◽  
Light Harvesting ◽  
Purple Bacteria ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Light Harvesting Complex Ii

scholarly journals A Study on the Heterogeneity of the Light-Harvesting Complex II from Ectothiorhodospira sp. after Acid/Chaotropic Treatment

2000 ◽  
Vol 55 (11-12) ◽  
pp. 943-947
Author(s):  
Andre Buche ◽  
Rafael Picorel
Keyword(s):  
Near Infrared ◽  
Light Harvesting ◽  
Purple Bacteria ◽  
Ionic Exchange ◽  
Absorption Bands ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Chromatographic Pattern ◽  
Light Harvesting Complex Ii ◽  
Polypeptide Backbone

The light-harvesting complex II of the purple bacteria has two strong near infrared electronic absorption bands, around 800 (B800) and 850 (B850) nm, arising from the Qy transitions of bacteriochlorophyll a. It was previously reported that under some specific acid/chaotropic conditions the B850 bacteriochlorophylls of the light-harvesting complex II of Ectothiorhodospira sp. are strongly reorganised. Part of these pigments absorbs at 843 nm while another set absorbs around 858 nm. The current work should investigate whether a mix of two different complexes could generate the 843- and 858-nm bands. Acid/chaotropic conditions inducing the reorganisation of B850 were reproduced on a sample bound to an ionic-exchange column. The chromatographic pattern was found strongly homogeneous. The findings indicate that the heterogeneity of the reorganised B850 results from two forms of differently structured bacteriochlorophylls bound to the same polypeptide backbone.

scholarly journals Observation of dissipative chlorophyll-to-carotenoid energy transfer in light-harvesting complex II in membrane nanodiscs

2019 ◽  
Author(s):  
Minjung Son ◽  
Alberta Pinnola ◽  
Samuel C. Gordon ◽  
Roberto Bassi ◽  
Gabriela S. Schlau-Cohen
Keyword(s):  
Energy Transfer ◽  
Conformational Changes ◽  
Light Harvesting ◽  
Electronic Spectroscopy ◽  
Local Environment ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Light Harvesting Complex Ii ◽  
Photosynthetic Antenna

<pre><p><a></a>Green plants prevent photodamage under high light conditions by dissipating excess energy as heat. Conformational changes of the photosynthetic antenna complexes activate dissipation by leveraging the sensitivity of the photophysics of the chlorophyll and carotenoids to their surrounding protein. However, the mechanisms and site of dissipation are still debated, largely due to two challenges. First, because of the ultrafast timescales and large energy gaps involved, measurements lacked the temporal or spectral requirements. Second, experiments have been performed in detergent, which can induce non-native conformations, or <i>in vivo</i>, where contributions from the multiple complexes cannot be disentangled and are further obfuscated by laser-induced artifacts. Here, we overcome both challenges by applying ultrabroadband two-dimensional electronic spectroscopy to the principal antenna complex, light-harvesting complex II, in a near-native membrane. The membrane enhances two dissipative pathways, one of which was previously uncharacterized chlorophyll-to-carotenoid energy transfer. Our results highlight the sensitivity of the photophysics to the local environment, which may be used to control the balance between light harvesting and dissipation <i>in vivo</i>.</p></pre>

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