Photoinduced electron transfer within supramolecular hemoprotein co-assemblies and heterodimers containing Fe and Zn porphyrins
Photoinduced electron transfer within supramolecular hemoprotein co-assemblies and heterodimers containing Fe and Zn porphyrins
复制标题
含铁、锌卟啉超分子血红素蛋白共组装体及异二聚体中的光诱导电子转移
DOI：
10.1016/j.jinorgbio.2019.01.001
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发表时间：
2019-04-01
影响因子：
3.9
通讯作者：
Hayashi, Takashi
中科院分区：
文献类型：
--
作者：
Kajihara, Ryota;Oohora, Koji;Hayashi, Takashi
金属蛋白复合物内发生的电子转移（ET）事件是生物系统中最重要的一类反应。本文描述了锌卟啉和铁卟啉在超分子细胞色素b(562) （Cyt b(562)）共组装或异源二聚体中的光诱导电子转移，该异源二聚体具有由金属卟啉-血红素口袋相互作用和蛋白质界面上的氢键网络形成的明确的刚性结构。在Cyt b（562）共组装和异源二聚体中均观察到光诱导电荷分离(CS: k（CS) = 320 ~ 600 s(-1)）和随后的电荷重组(CR: k（CR) = 580 ~ 930 s(-1)）。相比之下，有趣的是，在一个由灵活且结构不确定的共组装和在蛋白质界面缺乏关键氢键相互作用的异源二聚体组成的系统中，没有观察到ET事件。此外，利用Marcus方程对异源二聚体的CS和CR的动力学常数进行了分析，表明体系中发生了单步ET反应。这些发现提供了强有力的支持，即在蛋白质界面上含有适当的氢键网络的刚性血红蛋白组装系统对于监测ET反应至关重要。
Electron transfer (ET) events occurring within metalloprotein complexes are among the most important classes of reactions in biological systems. This report describes a photoinduced electron transfer between Zn porphyrin and Fe porphyrin within a supramolecular cytochrome b(562) (Cyt b(562)) co-assembly or heterodimer with a well-defined rigid structure formed by a metalloporphyrin-heme pocket interaction and a hydrogen-bond network at the protein interface. The photoinduced charge separation (CS: k(CS) = 320-600 s(-1)) and subsequent charge recombination (CR: k(CR) = 580-930 s(-1)) were observed in both the Cyt b(562) co-assembly and the heterodimer. In contrast, interestingly, no ET events were observed in a system comprised of a flexible and structurally-undefined co-assembly and heterodimers which lack the key hydrogen-bond interaction at the protein interface. Moreover, analysis of the kinetic constants of CS and CR of the heterodimer using the Marcus equation suggests that a single-step ET reaction occurs in the system. These findings provide strong support that the rigid hemoprotein-assembling system containing an appropriate hydrogen-bond network at the protein interface is essential for monitoring the ET reaction.