Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
J Phys Chem B. 2011 May 12;115(18):5083-95. doi: 10.1021/jp109833x. Epub 2011 Mar 31.
The time-resolved fluorescence intensity fluctuations from single, immobilized complexes of the main light-harvesting complex (LHCII) of plants were investigated in different pH environments close to room temperature and under different light conditions. The efficiency of light harvesting, which was represented by complexes typically residing for long periods in strongly fluorescing states, was significantly reduced by decreasing the pH or increasing the incident photon flux. The same environmental changes significantly increased the switching frequency between strongly and weakly fluorescing states. The environmental dependence became more evident when the various accessed intensity levels were first resolved, a technique that significantly reduced the obscuring effect of shot noise. The strong environmental sensitivity suggests that the immediate environment of an LHCII complex can modulate the amount of energy dissipation. A simple model illustrates how this may be achieved: the dynamic equilibrium between the strongly and weakly fluorescing states can be shifted by environmentally controlling the conformational diffusion on the potential energy surface of LHCII.
在接近室温的不同 pH 值环境中和不同光照条件下，研究了植物主要光捕获复合物（LHCII）的单个固定复合物的时间分辨荧光强度波动。通过降低 pH 值或增加入射光子通量，光捕获效率（以通常长时间处于强荧光状态的复合物为代表）显著降低。同样的环境变化显著增加了强荧光态和弱荧光态之间的转换频率。当首先解析各种访问的强度水平时，环境依赖性变得更加明显，该技术显著降低了散粒噪声的干扰。强烈的环境敏感性表明，LHCII 复合物的直接环境可以调节能量耗散的量。一个简单的模型说明了这是如何实现的：通过环境控制 LHCII 势能表面上的构象扩散，可以在强和弱荧光状态之间的动态平衡。
