کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5403985 | 1392770 | 2007 | 6 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Novel characteristics of persistent spectral hole-burning and hole-filling in Photosystem II core complexes
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
We report spectral hole-burning as well as spontaneous and photo-induced hole-filling in Photosystem II (PSII) core complexes. A comparison is made between measurements on initially dark-adapted PSII cores in which the plastoquinone QA is either neutral or photo-reduced to QA- by illumination at 1.7Â K, with samples where QA is reduced by either 260Â K illumination or chemical treatment. The latter preparations have the advantage of exhibiting minimal change in QA- with either time or illumination at 1.7Â K. This stability allowed us to investigate the association of rapid hole-filling reported for PSII core complexes with the spontaneous re-oxidation of QA-, which occurs in dark-adapted samples after 1.7Â K illumination. We find that spontaneous hole-filling also occurs in PSII with stable QA- configurations. In either class of sample, spontaneous hole-filling occurs at significantly greater rates than for 'normal' two level system hole-burning processes in chlorophyll-protein antenna complexes. It is suggested that the rapid spontaneous hole-filling is associated with protein relaxation within the energy landscape of the PSII core proteins. This landscape may also be involved in influencing other processes such as low-temperature QA reduction and re-oxidation. Shallow holes burnt in QA samples exhibit a narrow (â¼2cm-1) photoproduct on the low energy side of the hole. Subsequent illumination of holes burnt at 690Â nm with 705Â nm light induces strong hole-filling. These results are discussed with respect to charge and excitation energy transfer processes in PSII cores.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Luminescence - Volume 127, Issue 1, November 2007, Pages 239-244
Journal: Journal of Luminescence - Volume 127, Issue 1, November 2007, Pages 239-244
نویسندگان
Joseph L. Hughes, Elmars Krausz,