Fluctuating Two-State Light Harvesting in a Photosynthetic Membrane

详细信息    查看全文

• 作者：Duohai Pan ; Dehong Hu ; Ruchuan Liu ; Xiaohua Zeng ; Samuel Kaplan ; H. Peter Lu
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：June 28, 2007
• 年：2007
• 卷：111
• 期：25
• 页码：8948 - 8956
• 全文大小：485K
• 年卷期：v.111,no.25(June 28, 2007)
• ISSN：1932-7455

文摘

The mechanism by which light is converted into chemical energy in a natural photosynthetic system hasdrawn considerable research interest. Using fluorescence spectroscopy and microscopic imaging, we haveobserved fluctuating intermolecular protein fluorescence resonant energy transfers (FRET) among light-harvesting proteins I and II (LH1 and LH2) in bacterial photosynthetic membranes. Using two-channel, FRET,photon-counting detection and a novel, two-dimensional cross-correlation function amplitude-mapping analysis,we revealed fluorescence intensity and spectral fluctuations of donor (LH2) and acceptor (LH1) fluorescenceinvolving FRET. Our results suggest that there are dynamic coupled and noncoupled states of the light-harvesting protein assemblies in photosynthetic membranes. The light-harvesting complex assembly underambient conditions and under water involves dynamic intermolecular structural fluctuations that subsequentlydisturb the degree of energy transfer coupling between proteins in the membrane. Such intrinsic and dynamicheterogeneity of the native photosynthetic membranes, often submerged under the overall thermally inducedspectral fluctuations and not observable in an ensemble-averaged measurement, likely plays a critical role inregulating the light-harvesting efficiency of the photosynthetic membranes.