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Spectroscopic evidence for triplet excitation energy transfer among carotenoids in the LH2 complex from photosynthetic bacterium Rhodopseudomonas palustris
Feng, J; Wang, Q; Zhang, XJ; Huang, YG; Al, XC; Zhang, XK; Zhang, JP
2004-02-01
Source PublicationSCIENCE IN CHINA SERIES B-CHEMISTRY
ISSN1006-9291
Volume47Issue:1Pages:80-90
AbstractThe LH2 complex from Rhodopsudomonas (Rps.) palustris is unique in the heterogeneous carotenoid compositions. The dynamics of triplet excited state Carotenoids ((3)Car*) has been investigated by means of sub-microsecond time-resolved absorption spectroscopy both at physiological temperature (295 K) and at cryogenic temperature (77 K). Broad and asymmetric T-n <-- T-1 transient absorption was observed at room temperature following the photo-excitation of Car at 532 nm, which suggests the contribution from various carotenoid compositions having different numbers of conjugated C=C double bonds (N-C=C). The triplet absorption bands of different carotenoids, which superimposed at room temperature, could be clearly distinguished upon decreasing the temperature down to 77 K. At room temperature the shorter-wavelength side of the main T-n <-- T-1 absorption band decayed rapidly to reach a spectral equilibration with a characteristic time constant of similar to1 mus, the same spectral dynamics, however, was not observed at 77 K. The aforementioned spectral dynamics can be explained in terms of the triplet-excitation transfer among heterogeneous carotenoid compositions. Global spectral analysis was applied to the time-resolved spectra at room temperature, which revealed two spectral components peaked at 545 and 565 nm, and assignable to the T-n <-- T-1 absorption of Cars with N-C=C=11 and N-C=C=13, respectively. Surprisingly, the decay time constant of a shorter-conjugated Car, i.e. 0.72 mus (aerobic) and 1.36 mus (anaerobic), is smaller than that of a longer-conjugated Car, i.e. 2.12 mus (aerobic) and 3.75 mus (anaerobic), which is contradictory to the general rule of carotenoids and relative polyenes. The results are explained in terms of triplet-excitation transfer among different types of Cars. It is postulated that two Cars with different conjugation lengths coexist in an alpha, beta-subunit in the LH2 complex.
KeywordPurple Photosynthetic Bacteria Carotenoid Excited-state Time-resolved Spectroscopy
DOI10.1360/03yb0104
Indexed BySCI
Language英语
WOS IDWOS:000188966900011
PublisherSCIENCE CHINA PRESS
Citation statistics
Cited Times:4[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Identifierhttp://ir.iccas.ac.cn/handle/121111/81852
Collection中国科学院化学研究所
Corresponding AuthorZhang, JP
Affiliation1.Chinese Acad Sci, Inst Chem, State Key Lab Struct Chem Unstable & Stable Speci, Beijing 100080, Peoples R China
2.Chinese Acad Sci, Inst Biophys, Natl Lab Biomacromol, Beijing 100101, Peoples R China
Recommended Citation
GB/T 7714
Feng, J,Wang, Q,Zhang, XJ,et al. Spectroscopic evidence for triplet excitation energy transfer among carotenoids in the LH2 complex from photosynthetic bacterium Rhodopseudomonas palustris[J]. SCIENCE IN CHINA SERIES B-CHEMISTRY,2004,47(1):80-90.
APA Feng, J.,Wang, Q.,Zhang, XJ.,Huang, YG.,Al, XC.,...&Zhang, JP.(2004).Spectroscopic evidence for triplet excitation energy transfer among carotenoids in the LH2 complex from photosynthetic bacterium Rhodopseudomonas palustris.SCIENCE IN CHINA SERIES B-CHEMISTRY,47(1),80-90.
MLA Feng, J,et al."Spectroscopic evidence for triplet excitation energy transfer among carotenoids in the LH2 complex from photosynthetic bacterium Rhodopseudomonas palustris".SCIENCE IN CHINA SERIES B-CHEMISTRY 47.1(2004):80-90.
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