Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138;
Department of Chemistry, University of California, Berkeley, CA 94720;
Proc Natl Acad Sci U S A. 2018 Oct 9;115(41):E9523-E9531. doi: 10.1073/pnas.1806597115. Epub 2018 Sep 20.
An important determinant of crop yields is the regulation of photosystem II (PSII) light harvesting by energy-dependent quenching (qE). However, the molecular details of excitation quenching have not been quantitatively connected to the fraction of excitations converted to chemical energy by PSII reaction centers (PSII yield), which determines flux to downstream metabolism. Here, we incorporate excitation dissipation by qE into a pigment-scale model of excitation transfer and trapping for a 200 × 200-nm patch of the grana membrane. We show that excitation transport can be rigorously coarse grained to a 2D random walk with an excitation diffusion length determined by the extent of quenching. We present an alternative method for analyzing pulse amplitude-modulated chlorophyll fluorescence measurements that incorporates the effects of a variable excitation diffusion length during qE activation.
作物产量的一个重要决定因素是通过能量依赖的猝灭（qE）来调节光系统 II（PSII）的光捕获。然而，激发猝灭的分子细节尚未与 PSII 反应中心（PSII 产量）将激发转化为化学能的部分定量相关联，这决定了向下游代谢的通量。在这里，我们将 qE 引起的激发耗散纳入到一个 200x200nm 叶绿体膜薄片的激发转移和捕获的色素尺度模型中。我们表明，激发输运可以严格地粗化为二维随机漫步，激发扩散长度由猝灭的程度决定。我们提出了一种分析脉冲振幅调制叶绿素荧光测量的替代方法，该方法在 qE 激活期间考虑了可变激发扩散长度的影响。
