Wagner Heiko, Gilbert Matthias, Goss Reimund, Wilhelm Christian
Universität Leipzig, Biologie I/Abteilung Pflanzenphysiologie, Johannisallee 23, 04103 Leipzig, Germany.
J Photochem Photobiol B. 2006 Jun 1;83(3):172-9. doi: 10.1016/j.jphotobiol.2005.12.020. Epub 2006 Feb 20.
We have used chlorophyll fluorescence, delayed luminescence and thermoluminescence measurements to study the influence of an artificial DeltapH in the presence or absence of zeaxanthin on photosystem II reactions. Energization of the pea thylakoid membranes induced non-photochemical fluorescence quenching and an increase in the overall luminescence emission of PSII during delayed luminescence and thermoluminescence measurements. This DeltapH-induced overall luminescence increase was caused by a strongly enhanced delayed luminescence in the seconds range before sample heating. In the subsequent thermoluminescence measurements the intensity of the B-band decreased after one and increased after two or more single turnover flashes. We propose that strong membrane energization shifted the redox potential of photosystem II radical pairs to more negative values causing the high delayed luminescence. The zeaxanthin-dependent non-photochemical fluorescence quenching component, however, did not alter thermoluminescence B-bands but decreased the delayed luminescence intensity by 30%. To our knowledge this is the first report that the radiative radical pair recombination, exhibited as delayed luminescence but not thermoluminescence emission, is sensitive to the antenna located zeaxanthin related non-photochemical fluorescence quenching. Our data can be interpreted within the frame of the exciton/radical pair equilibrium model that describes photosystem II as a shallow trap and incorporates the transfer of energy from the re-excitated reaction centre to the antenna of photosystem II.
我们利用叶绿素荧光、延迟发光和热发光测量方法，研究了在有或没有玉米黄质存在的情况下，人工跨膜质子梯度（ΔpH）对光系统II反应的影响。在延迟发光和热发光测量过程中，豌豆类囊体膜的质子动力势激发诱导了非光化学荧光猝灭，并使光系统II的整体发光发射增强。这种由ΔpH诱导的整体发光增强是由样品加热前几秒内强烈增强的延迟发光引起的。在随后的热发光测量中，单周转闪光一次后B带强度降低，闪光两次或更多次后B带强度增加。我们认为，强烈的膜质子动力势使光系统II自由基对的氧化还原电位向更负值移动，从而导致高延迟发光。然而，依赖玉米黄质的非光化学荧光猝灭成分并没有改变热发光B带，但使延迟发光强度降低了30%。据我们所知，这是第一份关于以延迟发光而非热发光发射表现出的辐射性自由基对复合对位于天线的与玉米黄质相关的非光化学荧光猝灭敏感的报告。我们的数据可以在激子/自由基对平衡模型的框架内进行解释，该模型将光系统II描述为一个浅陷阱，并纳入了从再激发的反应中心到光系统II天线的能量转移。
