Function and Physical Chemistry of a Novel Porphyrin Isomer, Corrphycene.

新型卟啉异构体 Corrphycene 的功能和物理化学。

• 批准号: 10672031
• 负责人: NEYA Saburo
• 金额: $ 1.54万
• 依托单位: Kyoto Pharmaceutical University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10672031/
• 关键词: Corrphycene; Iron Reactivity; Protein Reconstitution; Myoglobin; Spin State; Ligand Binding; Oxygen; Carbon Monoxide; 酸素運搬体; 人工ミオグロビン; 配位子化学; イミダゾール; 平衡定数; ポルフィリン異性体; 酵素結合たんぱく質; ポルフィリン; 有機合成; 一酸化炭素結合

Purpose of the proposed research is the functional and physicochemical analysis of a novel structural isomer of porphyrin, corrphycene. The meso-carbon array in corrphycene is in (2, 1, 0, 1), in remarkable contrast with the (1, 1, 1, 1) array in regular porphyrin. The metal cavity in corrphycene is trapezoidal. The reactivity of the iron atom in trapezoidal core is expected to be distinct from that of regular heme iron.The reactivity of iron (III) corrphycene in organic solvent toward 1-methylimidazole was examined. Spectroscopic analysis revealed the appreciable accumulation mono-adduct of 1-methylimidazole during the ligand titration, contrary to iron (III) porphyrin that does not form the mono-adduct. The observation in corrphycene demonstrates that the out-of-plane configuration of iron atom is stabilized with the trapezoidal deformation of e metal cavity.We further analyzed the biological function of iron (II) corrphycene as the prosthetic group of hemoprotein. The myoglobin reco … More nstituted with ferrous corrphycene was fund to be functionally active to reversibly bind oxygen and carbon monoxide. Quantitative analysis, however, revealed that the functional anomalies : the association constants for oxygen and carbon monoxide are extremely low. The affinities of etiocorrphycene-substituted myoglobin for oxygen and carbon monoxide are only 1/13 and 1/128, respectively, as compared with those of native myoglobin. The infrared analysis of corrphycene myoglobin indicates that the iron-CO bond is weakened. The functional and structural anomalies are suggested to arise from decreased iron-CO interactions owing to the larger iron (II) displacement from the plane of corrphycene.The azide complex of iron (III) corrphycene is in an equilibrium between the high-(S=5/2) and low-spin (S=1/2) states, and the equilibrium position is much susceptible to the core deformation of the porphyrin macrocycle. We investigated the magnetic property of the iron (III) in the azide complex of corrphycene myoglobin to support the larger displacement of the iron in corrphycene. The temperature-dependent visible absorption changes revealed that the iron (III) is 80% high-spin. The high-spin fraction is one-order of magnitude larger than 8% reported for native myoglobin. The accompanied infrared observation consistently indicated that the high-spin band is 4-fold larger than the low-spin peak. The anomalous high-spin bias of the equilibrium is fully consistent with the large displacement of the iron from the corrphycene plane. The electron spin resonance spectrum of azide complex demonstrates that the iron-histidine bond is cleaved at 5 K.Anomalous break of the iron-histidine bond was ascribed to the weakened axial bond of the corrphycene-substituted myoglobin.In summary, we revealed unique properties of the iron corrphycene. The abilities of corrphycene iron are substantially modified by the geometric strain in the equatorial coordination core. Therefore, corrphycene is a promissing and potential modulator of the functions of hemoproteins. Less

本研究的目的是对卟啉的一种新型结构异构体-卟啉进行功能和物理化学分析。卟啉中的中间相碳排列为（2，1，0，1），与规则卟啉中的（1，1，1，1）排列形成明显的对比。在corrphycene的金属腔是梯形的。梯形核中的铁原子的反应性与规则的血红素铁不同。研究了铁（III）卟啉在有机溶剂中对1-甲基咪唑的反应性。光谱分析显示，在配体滴定过程中的1-甲基咪唑的可观的积累单加合物，相反，铁（III）卟啉，不形成单加合物。通过对卟啉的观察，证明铁原子的面外构型随着金属腔的梯形形变而稳定，并进一步分析了卟啉铁作为血红素蛋白辅基的生物学功能。肌红蛋白Reco ...更多信息 发现被亚铁卟啉取代的化合物具有可逆结合氧和一氧化碳的功能活性。然而，定量分析表明，功能异常：氧和一氧化碳的缔合常数非常低。与天然肌红蛋白相比，原卟啉取代的肌红蛋白对氧和一氧化碳的亲和力分别仅为1/13和1/128。红紫质肌红蛋白的红外分析表明铁-CO键被削弱。Fe（II）从卟啉平面上的位移较大，导致Fe（III）与CO的相互作用减弱，从而导致功能和结构的异常. Fe（III）卟啉的叠氮配合物处于高自旋（S=5/2）和低自旋（S=1/2）态之间的平衡，平衡位置对卟啉大环的核变形非常敏感.我们研究了铁（III）的叠氮配合物的corrphycene肌红蛋白的磁性，以支持更大的位移的铁在corrphycene。随温度变化的可见光吸收变化表明，铁（III）是80%的高自旋。高自旋分数是一个数量级大于8%的报告为天然肌红蛋白。伴随的红外观测一致地表明，高自旋带比低自旋峰大4倍。平衡的反常高自旋偏置与铁从堇青石平面的大位移完全一致。叠氮化合物的电子自旋共振谱表明铁-组氨酸键在5 K时发生断裂，铁-组氨酸键的异常断裂归因于铁卟啉取代的肌红蛋白的轴向键的弱化，揭示了铁卟啉的独特性质.在赤道配位核的几何应变的能力大大修改corrphycene铁。因此，紫堇烯是一种很有前途的血红素蛋白功能调节剂。少

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