Rankelytė Gabrielė, Gelzinis Andrius, Robert Bruno, Valkunas Leonas, Chmeliov Jevgenij
Institute of Chemical Physics, Faculty of Physics, Vilnius University, Vilnius, Lithuania.
Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Vilnius, Lithuania.
Front Plant Sci. 2024 Aug 7;15:1412750. doi: 10.3389/fpls.2024.1412750. eCollection 2024.
Photosystem I (PSI) light-harvesting antenna complexes LHCI contain spectral forms that absorb and emit photons of lower energy than that of its primary electron donor, P700. The most red-shifted fluorescence is associated with the Lhca4 complex. It has been suggested that this red emission is related to the inter-chlorophyll charge transfer (CT) states. In this work we present a systematic quantum-chemical study of the CT states in Lhca4, accounting for the influence of the protein environment by estimating the electrostatic interactions. We show that significant energy shifts result from these interactions and propose that the emission of the Lhca4 complex is related not only to the previously proposed 603-608 state, but also to the 602-603 state. We also investigate how different protonation patterns of protein amino acids affect the energetics of the CT states.
光系统I（PSI）捕光天线复合物LHCI包含一些光谱形式，它们吸收和发射的光子能量低于其原初电子供体P700的光子能量。红移最大的荧光与Lhca4复合物相关。有人提出这种红色发射与叶绿素间电荷转移（CT）态有关。在这项工作中，我们对Lhca4中的CT态进行了系统的量子化学研究，通过估计静电相互作用来考虑蛋白质环境的影响。我们表明这些相互作用会导致显著的能量位移，并提出Lhca4复合物的发射不仅与先前提出的603 - 608态有关，还与602 - 603态有关。我们还研究了蛋白质氨基酸的不同质子化模式如何影响CT态的能量学。
