The efficiency of non-photochemical fluorescence quenching by cation radicals in photosystem II reaction centers

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• 作者：V. Z. Paschenko ; A. A. Churin ; V. V. Gorokhov ; N. P. Grishanova…
• 关键词：Photosystem II ; Non ; photochemical quenching ; Photochemical reactions ; Light ; harvesting antenna ; Reaction center
• 刊名：Photosynthesis Research
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：130
• 期：1-3
• 页码：325-333
• 全文大小：724 KB
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Life Sciences
  Plant Physiology
  
• 出版者：Springer Netherlands
• ISSN：1573-5079
• 卷排序：130

文摘

In a direct experiment, the rate constants of photochemical k_p and non-photochemical k_p+ quenching of the chlorophyll fluorescence have been determined in spinach photosystem II (PS II) membrane fragments, oxygen-evolving PS II core, as well as manganese-depleted PS II particles using pulse fluorimetry. In the dark-adapted reaction center(s) (RC), the fluorescence decay kinetics of the antenna were measured at low-intensity picosecond pulsed excitation. To create a “closed” P680+Q_A− state, RCs were illuminated by high-intensity actinic flash 8 ns prior to the measuring flash. The obtained data were approximated by the sum of two decaying exponents. It was found that the antennae fluorescence quenching efficiency by the oxidized photoactive pigment of RC P680+ was about 1.5 times higher than that of the neutral P680 state. These results were confirmed by a single-photon counting technique, which allowed to resolve the additional slow component of the fluorescence decay. Slow component was assigned to the charge recombination of P680+Pheo− in PS II RC. Thus, for the first time, the ratio k_p+/k_p ≅ 1.5 was found directly. The mechanism of the higher efficiency of non-photochemical quenching comparing to photochemical quenching is discussed.