Iron hemiporphycene as a functional prosthetic group for myoglobin
Iron hemiporphycene as a functional prosthetic group for myoglobin
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DOI：
10.1021/ic020504t
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发表时间：
2003-03-10
影响因子：
4.6
通讯作者：
Funasaki, N
中科院分区：
文献类型：
--
作者：
Neya, S;Imai, K;Funasaki, N
半卟啉的铁配合物，卟啉与卟啉的分子杂化物，被纳入脱辅基肌红蛋白口袋中，以检查新的卟啉类中的铁原子的配体结合能力。将脱辅基肌红蛋白与化学计量的铁半卟啉偶联，得到具有天然蛋白质的铁配位结构的重组肌红蛋白。氰化物，咪唑，和氟化物协调与天然肌红蛋白的亲和力与铁蛋白。亚铁肌红蛋白在pH7.4和20 ℃下具有可逆结合O-2和CO的功能活性。O-2亲和力比天然肌红蛋白高12倍，而CO亲和力略低，表明血红素口袋中O-2和CO之间的区分降低。的功能异常被解释为反映增加σ键合特征的Fe（II）-O-2键。与6配位的天然NO蛋白相比，含亚铁半卟啉的NO肌红蛋白处于5-和6-配位的混合状态。这一观察结果表明，在hemiphoprophicene的铁原子的面内配置是不稳定的NO。核心变形的影响也检测到与两个红外吸收的亚铁CO衍生物和电子顺磁共振铁咪唑络合物。铁和亚铁衍生物中的异常归因于半卟啉的不对称金属核中的改性铁-N（吡咯）相互作用。
The iron complex of hemiporphycene, a molecular hybrid of porphyrin with porphycene, was incorporated into the apomyoglobin pocket to examine ligand binding ability of the iron atom in the novel porphyrinoid. Apomyoglobin was successfully coupled with a stoichiometric amount of ferric hemiporphycene to afford the reconstituted myoglobin equipped with the iron coordination structure of native protein. Cyanide, imidazole, and fluoride coordinated to the ferric protein with affinities comparable with those for native myoglobin. The ferrous myoglobin was functionally active to bind O-2 and CO reversibly at pH 7.4 and 20 degreesC. The O-2 affinity is 12-fold higher than that of native myoglobin while the CO affinity is slightly lower, suggesting decreased discrimination between O-2 and CO in the heme pocket. The functional anomaly was interpreted to reflect increased sigma-bonding character in the Fe(II)-O-2 bond. In contrast with 6-coordinate native NO protein, the NO myoglobin containing ferrous hemiporphycene is in a mixed 5- and 6-coordinate state. This observation suggests that the in-plane configuration of the iron atom in hemiporphycene is destabilized by NO. Influence of the core deformation was also detected with both the infrared absorption for the ferrous CO derivative and electron paramagnetic resonance for ferric imidazole complex. Anomalies in the ferric and ferrous derivatives were ascribed to the modified iron-N(pyrrole) interactions in the asymmetric metallo core of hemiporphycene.