Ruban AV, Horton P
Robert Hill Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
Plant Physiol. 1999 Feb;119(2):531-42. doi: 10.1104/pp.119.2.531.
We analyzed the kinetics of nonphotochemical quenching of chlorophyll fluorescence (qN) in spinach (Spinacia oleracea) leaves, chloroplasts, and purified light-harvesting complexes. The characteristic biphasic pattern of fluorescence quenching in dark-adapted leaves, which was removed by preillumination, was evidence of light activation of qN, a process correlated with the de-epoxidation state of the xanthophyll cycle carotenoids. Chloroplasts isolated from dark-adapted and light-activated leaves confirmed the nature of light activation: faster and greater quenching at a subsaturating transthylakoid pH gradient. The light-harvesting chlorophyll a/b-binding complexes of photosystem II were isolated from dark-adapted and light-activated leaves. When isolated from light-activated leaves, these complexes showed an increase in the rate of quenching in vitro compared with samples prepared from dark-adapted leaves. In all cases, the quenching kinetics were fitted to a single component hyperbolic function. For leaves, chloroplasts, and light-harvesting complexes, the presence of zeaxanthin was associated with an increased rate constant for the induction of quenching. We discuss the significance of these observations in terms of the mechanism and control of qN.
我们分析了菠菜（Spinacia oleracea）叶片、叶绿体和纯化的光捕获复合物中叶绿素荧光非光化学猝灭（qN）的动力学。暗适应叶片中荧光猝灭的特征性双相模式可通过预照光消除，这证明了qN的光激活，该过程与叶黄素循环类胡萝卜素的脱环氧化状态相关。从暗适应和光激活叶片中分离出的叶绿体证实了光激活的性质：在亚饱和的跨类囊体pH梯度下猝灭更快且更强。从暗适应和光激活叶片中分离出光系统II的光捕获叶绿素a/b结合复合物。与从暗适应叶片制备的样品相比，当从光激活叶片中分离时，这些复合物在体外显示出猝灭速率增加。在所有情况下，猝灭动力学均符合单组分双曲线函数。对于叶片、叶绿体和光捕获复合物，玉米黄质的存在与猝灭诱导的速率常数增加相关。我们根据qN的机制和控制来讨论这些观察结果的意义。
