Pressure Effect on Zero-Field Splitting Parameter of Hemin: Model Case of Hemoproteins under Pressure
Pressure Effect on Zero-Field Splitting Parameter of Hemin: Model Case of Hemoproteins under Pressure
复制标题
压力对血红素零场分裂参数的影响：压力下血红素蛋白的模型案例
DOI：
10.1021/acs.jpcb.8b03128
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Hitoshi Ohta
中科院分区：
文献类型：
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作者：
Tsubasa Okamoto;Eiji Ohmichi;Yu Saito;Takahiro Sakurai;Hitoshi Ohta
利用高频和高场电子顺磁共振（HFEPR）实验研究了血红蛋白模型复合物血红蛋白（铁（III）原卟啉IX氯）在压力下零场分裂（ZFS）参数的压力依赖性。由于ZFS较大，压力对铁卟啉配合物电子结构的影响尚未用EPR进行研究。因此，我们使用新开发的次太赫兹EPR光谱系统，在80-515 GHz频率范围内，在高达10 T的磁场和高达2 GPa的压力下系统地研究了这种效应。我们观察到hemin的共振场在施加压力时发生了系统的变化，ZFS参数的轴向分量从md = 6.9增加到7.9 cm-1at 2 GPa。与以往研究压力下蛋白质的方法主要关注构象变化不同，我们的HFEPR技术可以更微观地了解压力下金属离子的电子结构。从这个意义上说，我们的技术为研究压力对多功能金属蛋白生物功能活性中心的影响提供了新的机会。
We experimentally studied the pressure dependence of the zero-field splitting (ZFS) parameter of hemin (iron(III) protoporphyrin IX chloride), which is a model complex of hemoproteins, via high-frequency and high-field electron paramagnetic resonance (HFEPR) under pressure. Owing to the large ZFS, the pressure effect on the electronic structure of iron–porphyrin complexes has not yet been explored using EPR. Therefore, we systematically studied this effect using our newly developed sub-terahertz EPR spectroscopy system in the frequency range of 80–515 GHz, under magnetic fields up to 10 T and pressure up to 2 GPa. We observed a systematic shift of the resonance fields of hemin upon pressure application, from which the axial component of the ZFS parameter was found to increase fromD= 6.9 to 7.9 cm–1at 2 GPa. In contrast to the previous methods used to study proteins under pressure, which mainly focused on conformational changes, our HFEPR technique can obtain more microscopic insights into the electronic structures of metal ions under pressure. In this sense, our technique provides novel opportunities to study the pressure effects on biofunctional active centers of versatile metalloproteins.