کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5372652 | 1504181 | 2017 | 11 صفحه PDF | دانلود رایگان |
- The LH2 antenna of Rbl. acidophila can exist in metastable conformations.
- These conformations are formed by ligation between adjacent bacteriochlorophylls a.
- These conformations can be formed by thermal or photochemical activation.
- The B850 band of the LH2 complex in metastable conformation exhibits red shift.
Single-molecule spectroscopic experiments on several light-harvesting complexes revealed the existence of a set of metastable conformational states with different spectroscopic properties and lifetimes spanning from milliseconds to tens of seconds. In the absence of explicit structural data, a number of probable structural changes underlying the observed spectroscopic shifts were proposed. We examine the donor-acceptor interaction between the magnesium atom and the acetyl group of the adjacent bacteriochlorophylls a as a possible origin of metastable conformational states in the LH2 light-harvesting complex of Rbl. acidophilus bacteria. The results of QM/MM and molecular dynamics simulations show that such ligation can occur at room temperature and leads to one metastable coordination bond per pair of bacteriochlorophylls in the B850 ring. According to the results of Poisson-TrESP modeling, such coordination lowers the energies of the excited states of the complex by up to 163Â cmâ1 which causes red spectral shift of the B850 band.
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Journal: Chemical Physics - Volume 490, 20 June 2017, Pages 81-91