Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, De Boelelaan, Amsterdam, The Netherlands.
Biophys J. 2012 Jun 6;102(11):2669-76. doi: 10.1016/j.bpj.2012.04.044. Epub 2012 Jun 5.
The light-harvesting antenna of photosystem II (PSII) has the ability to switch rapidly between a state of efficient light use and one in which excess excitation energy is harmlessly dissipated as heat, a process known as qE. We investigated the single-molecule fluorescence intermittency of the main component of the PSII antenna (LHCII) under conditions that mimic efficient use of light or qE, and we demonstrate that weakly fluorescing states are stabilized under qE conditions. Thus, we propose that qE is explained by biological control over the intrinsic dynamic disorder in the complex-the frequencies of switching establish whether the population of complexes is unquenched or quenched. Furthermore, the quenched states were accompanied by two distinct spectral signatures, suggesting more than one mechanism for energy dissipation in LHCII.
光合作用系统 II（PSII）的光捕获天线具有在高效光能利用状态和将多余激发能无害地耗散为热能的状态之间快速切换的能力，这一过程称为 qE。我们在模拟高效光能利用或 qE 的条件下研究了 PSII 天线的主要成分（LHCII）的单分子荧光间歇性，并证明在 qE 条件下稳定了弱荧光状态。因此，我们提出 qE 是通过对复合物内在动态无序的生物控制来解释的——转换频率确定复合物的群体是否被猝灭或未猝灭。此外，猝灭状态伴随着两个不同的光谱特征，这表明 LHCII 中存在不止一种能量耗散机制。
