New Insights into the Mechanism of Uphill Excitation Energy Transfer from Core Antenna to Reaction Center in Purple Photosynthetic Bacteria

2018 ◽  
Vol 9 (12) ◽  
pp. 3278-3284 ◽  
Author(s):  
Li-Ming Tan ◽  
Jie Yu ◽  
Tomoaki Kawakami ◽  
Masayuki Kobayashi ◽  
Peng Wang ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Reaction Center ◽  
Photosynthetic Bacteria ◽  
Excitation Energy Transfer ◽  
Purple Photosynthetic Bacteria

scholarly journals Sensitivity of Antarctic freshwater algae to salt stress assessed by fast chlorophyll fluorescence transient

2013 ◽  
Vol 3 (2) ◽  
pp. 163-172 ◽  
Author(s):  
David Miguel Vilumbrales ◽  
Kateřina Skácelová ◽  
Miloš Barták
Keyword(s):  
Energy Transfer ◽  
Salt Stress ◽  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Excitation Energy ◽  
Reaction Center ◽  
Excitation Energy Transfer ◽  
Ps Ii ◽  
Fluorescence Transient ◽  
Chlorophyll Fluorescence Transient

In this study, we investigated the effects of salt stress (2 mM NaCl) on excitation energy transfer from light harvesting complexes to photosystem II (PS II) in two Antarctic algal species: Klebsormidium sp. and Zygnema sp. Short-term salt stress led to a significant changes in the shape of chlorophyll fluorescence transient (OJIP). Analyses of the polyphasic fluorescence transients (OJIP) showed that the fluorescence yield at the phases J, I and P declined considerably with the time of exposition to salt stress. In both experimental species, OJIP transients reached lowest values of chlorophyll fluorescence signal after 30/60 min. of NaCl exposition. Then, OJIP shape and chlorophyll fluo-rescence showed species-specific recovery and rised towards original values (about 2/3 of untreated control). Analyses of chlorophyll fluorescence parameters derived from OJIPs showed that salt stress led to a decrease in the maximal efficiency of PS II photo-chemistry (FV/FM) in Zygnema sp. but not Klebsormidium sp. The results indicated that the probability of excitation energy transfer before and beyond QA, and the yield of electron transport beyond QA is limited by salt-induced stress in Zygnema sp. In addition, salt stress resulted in a decrease in the photosynthetic electron transport per PS II reaction center, but both increase and decrease in the trapping per PS II reaction center was found. Performace index (PIabs) was affected negatively in Zygnema sp. but possitively Klebsormidium sp. indicating that the latter species was more resistant to salt stress than Zygnema sp.

Photosynthesis

2009 ◽  
pp. 573-587
Author(s):  
Julia Adolphs
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Reaction Center ◽  
High Efficiency ◽  
Excitation Energy Transfer ◽  
Photosynthetic Reaction Center ◽  
Photochemical Reactions ◽  
Light Harvesting Complexes ◽  
Transition Energies ◽  
Local Transition

This chapter introduces the theory of optical spectra and excitation energy transfer of light harvesting complexes in photosynthesis. The light energy absorbed by protein bound pigments in these complexes is transferred via an exciton mechanism to the photosynthetic reaction center where it drives the photochemical reactions. The protein holds the pigments in optimal orientation for excitation energy transfer and creates an energy sink by shifting the local transition energies of the pigments. In this way, the excitation energy is directed with high efficiency (close to 100 %) to the reaction center. In the present chapter, this energy transfer is studied theoretically. Based on crystal structure data, the excitonic couplings are calculated taking into account also the polarizability of the protein. The local transition energies are obtained by two independent methods and are used to predict the orientation of the FMO protein relative to the reaction center.

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