Department of Physics, University of Dhaka, Dhaka 1000, Bangladesh.
Department of Physics, University of Pretoria, Pretoria 0023, South Africa.
Biochim Biophys Acta Bioenerg. 2020 Jul 1;1861(7):148187. doi: 10.1016/j.bbabio.2020.148187. Epub 2020 Mar 12.
Phycobilisomes (PBs) absorb light and supply downstream photosynthetic processes with excitation energy in many cyanobacteria and algae. In response to a sudden increase in light intensity, excess excitation energy is photoprotectively dissipated in PBs by means of the orange carotenoid protein (OCP)-related mechanism or via a light-activated intrinsic decay channel. Recently, we have identified that both mechanisms are associated with far-red emission states. Here, we investigate the far-red states involved with the light-induced intrinsic mechanism by exploring the energy landscape and electro-optical properties of the pigments in PBs. While Stark spectroscopy showed that the far-red states in PBs exhibit a strong charge-transfer (CT) character at cryogenic temperatures, single molecule spectroscopy revealed that CT states should also be present at room temperature. Owing to the strong environmental sensitivity of CT states, the knowledge gained from this study may contribute to the design of a new generation of fluorescence markers.
藻胆体（PBs）在许多蓝藻和藻类中吸收光，并将激发能供给下游光合作用过程。在光强突然增加时，过剩的激发能通过橙色类胡萝卜素蛋白（OCP）相关机制或通过光激活的内在衰减通道以光保护的方式耗散。最近，我们已经确定这两种机制都与远红光发射态有关。在这里，我们通过研究 PBs 中色素的能量景观和光电特性来研究与光诱导内在机制相关的远红光状态。虽然斯塔克光谱表明 PBs 中的远红光态在低温下表现出强烈的电荷转移（CT）特征，但单分子光谱表明 CT 态也应该存在于室温下。由于 CT 态对环境非常敏感，因此，从这项研究中获得的知识可能有助于设计新一代荧光标记物。
