PMID- 29053262
OWN - NLM
STAT- MEDLINE
DCOM- 20180105
LR  - 20180105
IS  - 1520-5126 (Electronic)
IS  - 0002-7863 (Linking)
VI  - 139
IP  - 44
DP  - 2017 Nov 8
TI  - Carotenoid Singlet Fission Reactions in Bacterial Light Harvesting Complexes As 
      Revealed by Triplet Excitation Profiles.
PG  - 15984-15993
LID - 10.1021/jacs.7b09809 [doi]
AB  - Carotenoids (Cars) in bacterial photosynthesis are known as accessory light 
      harvesters and photoprotectors. Recently, the singlet fission (SF) reaction 
      initiated by Car photoabsorption has been recognized to be an effective 
      excitation deactivation channel disfavoring the light harvesting function. Since 
      the SF reaction and the triplet sensitization reaction underlying photoprotection 
      both yield triplet excited state Cars ((3)Car*), their contribution to the 
      overall (3)Car* photoproduction are difficult to disentangle. To tackle this 
      problem, we resorted to the triplet excitation profiles (TEPs), i.e., the actinic 
      spectra of the overall (3)Car* photoproduction. The TEPs combined with the 
      conventional fluorescence excitation spectra allowed us to extract the neat SF 
      contribution, which can serve as a spectroscopic measure for the SF reactivity. 
      This novel spectroscopic strategy was applied to analyze the light harvesting 
      complexes (LHs) from Tch. tepidum and Rba. sphaeroides 2.4.1. The results 
      unambiguously showed that the SF reaction of Cars proceeds with an intramolecular 
      scheme, even in the case of LH1-RC from Rba. sphaeroides 2.4.1 likely binding a 
      secondary pool of Cars. Regarding the SF-reactivity, the geometric distortion in 
      the conjugated backbone of Cars was shown to be the structural determinant, while 
      the length of the Car conjugation was suggested to be relevant to the effective 
      localization of the geminate triplets to avoid being annihilated. The SF reaction 
      scheme and structure-activity relationship revealed herein will be useful not 
      only in deepening our understanding of the roles of Cars in photosynthesis, but 
      also in enlightening the applications of Cars in artificial light conversion 
      systems.
FAU - Yu, Jie
AU  - Yu J
AD  - Department of Chemistry, Renmin University of China , Beijing 100872, P. R. 
      China.
FAU - Fu, Li-Min
AU  - Fu LM
AD  - Department of Chemistry, Renmin University of China , Beijing 100872, P. R. 
      China.
FAU - Yu, Long-Jiang
AU  - Yu LJ
AD  - Faculty of Science, Ibaraki University , Mito 310-8512, Japan.
AD  - Department of Biology, Faculty of Science, Okayama University , Okayama 700-8530, 
      Japan.
FAU - Shi, Ying
AU  - Shi Y
AD  - Department of Chemistry, Renmin University of China , Beijing 100872, P. R. 
      China.
FAU - Wang, Peng
AU  - Wang P
AD  - Department of Chemistry, Renmin University of China , Beijing 100872, P. R. 
      China.
FAU - Wang-Otomo, Zheng-Yu
AU  - Wang-Otomo ZY
AD  - Faculty of Science, Ibaraki University , Mito 310-8512, Japan.
FAU - Zhang, Jian-Ping
AU  - Zhang JP
AUID- ORCID: 0000-0002-9216-2386
AD  - Department of Chemistry, Renmin University of China , Beijing 100872, P. R. 
      China.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20171026
PL  - United States
TA  - J Am Chem Soc
JT  - Journal of the American Chemical Society
JID - 7503056
RN  - 0 (Bacterial Proteins)
RN  - 0 (Light-Harvesting Protein Complexes)
RN  - 36-88-4 (Carotenoids)
SB  - IM
MH  - Bacterial Proteins/*chemistry/metabolism
MH  - Carotenoids/*chemistry/metabolism
MH  - Chromatiaceae/*chemistry/metabolism
MH  - Light
MH  - Light-Harvesting Protein Complexes/*chemistry/metabolism
MH  - Models, Molecular
MH  - Rhodobacter sphaeroides/*chemistry/metabolism
EDAT- 2017/10/21 06:00
MHDA- 2018/01/06 06:00
CRDT- 2017/10/21 06:00
PHST- 2017/10/21 06:00 [pubmed]
PHST- 2018/01/06 06:00 [medline]
PHST- 2017/10/21 06:00 [entrez]
AID - 10.1021/jacs.7b09809 [doi]
PST - ppublish
SO  - J Am Chem Soc. 2017 Nov 8;139(44):15984-15993. doi: 10.1021/jacs.7b09809. Epub 
      2017 Oct 26.