Department of Chemistry and Biochemistry , Freie Universität Berlin , Arnimallee 22 , 14195 Berlin , Germany.
J Phys Chem B. 2019 Dec 19;123(50):10594-10604. doi: 10.1021/acs.jpcb.9b07915. Epub 2019 Dec 5.
The water-soluble chlorophyll-binding protein (WSCP) is assumed to be not a part of the photosynthetic process. Applying molecular dynamics (MD) simulations, we aimed to obtain insight into the exceptional stability of WSCP. We analyzed dynamical features such as the hydrogen bond network, flexibility, and force distributions. The WSCP structure contains two cysteines at the interfaces of every protein chain, which are in close contact with the cysteines of the other dimer. We tested if a connection of these cysteines between different protein chains influences the dynamical behavior to investigate any influences on the thermal stability. We find that the hydrogen bond network is very stable regardless of the presence or absence of the hypothetical disulfide bridges and/or the chlorophyll units. Furthermore, it is found that the phytyl chains of the chlorophyll units are extremely flexible, much more than what is seen in crystal structures. Nonetheless, they seem to protect a photochemically active site of the chlorophylls over the complete simulation time. Finally, we also find that a cavity in the chlorophyll-surrounding sheath exists, which may allow access for individual small molecules to the core of WSCP.
水溶性叶绿素结合蛋白（WSCP）被认为不是光合作用过程的一部分。应用分子动力学（MD）模拟，我们旨在深入了解 WSCP 的异常稳定性。我们分析了氢键网络、灵活性和力分布等动态特征。WSCP 结构在每个蛋白质链的界面处包含两个半胱氨酸，它们与另一个二聚体的半胱氨酸密切接触。我们测试了不同蛋白质链之间的这些半胱氨酸的连接是否会影响动力学行为，以研究对热稳定性的任何影响。我们发现，氢键网络非常稳定，无论是否存在假设的二硫键和/或叶绿素单元。此外，还发现叶绿素单元的植基链非常灵活，比晶体结构中看到的要灵活得多。尽管如此，它们似乎在整个模拟时间内保护了叶绿素的光化学活性位点。最后，我们还发现叶绿素周围鞘中的一个空腔可能允许单个小分子进入 WSCP 的核心。
