Crystal structure and peroxidase activity of myoglobin reconstituted with iron porphycene
Crystal structure and peroxidase activity of myoglobin reconstituted with iron porphycene
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DOI：
10.1021/ic061130x
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发表时间：
2006-12-25
影响因子：
4.6
通讯作者：
Hisaeda, Yoshio
中科院分区：
文献类型：
--
作者：
Hayashi, Takashi;Murata, Dai;Hisaeda, Yoshio
将人工合成的金属配合物掺入到去氧肌红蛋白中是血红素蛋白修饰的一种有吸引力的方法。用13，16-二羧乙基-2，7-二乙基-3，6，12，17-四甲基卟啉合铁（III）在咪唑缓冲液中重构抹香鲸肌红蛋白的单晶，其2.25埃分辨率的三维结构表明，铁卟啉是氯化血红素的结构异构体，位于血红素口袋的正常位置。此外，还发现重建的肌红蛋白催化愈创木酚、茴香硫醚和苯乙烯等底物的H2 O2依赖性氧化。在pH 7.0和20摄氏度下，愈创木酚氧化的初始速率比观察到的天然肌红蛋白快11倍。此外，停流分析的重构蛋白质与H2 O2的反应表明，在没有底物的情况下，形成两个反应中间体，化合物II-和III-样的物种。在肌红蛋白化学中，化合物III通过化合物II形成是一个罕见的例子。铁卟啉对肌红蛋白过氧化物酶活性的增强和稳定化合物Ⅲ的形成主要是由于Fe-His 93键的强配位作用。
The incorporation of an artificially created metal complex into an apomyoglobin is one of the attractive methods in a series of hemoprotein modifications. Single crystals of sperm whale myoglobin reconstituted with 13,16-dicarboxyethyl-2,7-diethyl-3,6,12,17-tetramethylporphycenatoiron(III) were obtained in the imidazole buffer, and the 3D structure with a 2.25-angstrom resolution indicates that the iron porphycene, a structural isomer of hemin, is located in the normal position of the heme pocket. Furthermore, it was found that the reconstituted myoglobin catalyzed the H2O2-dependent oxidations of substrates such as guaiacol, thioanisole, and styrene. At pH 7.0 and 20 degrees C, the initial rate of the guaiacol oxidation is 11-fold faster than that observed for the native myoglobin. Moreover, the stopped-flow analysis of the reaction of the reconstituted protein with H2O2 suggested the formation of two reaction intermediates, compounds II- and III-like species, in the absence of a substrate. It is a rare example that compound III is formed via compound II in myoglobin chemistry. The enhancement of the peroxidase activity and the formation of the stable compound III in myoglobin with iron porphycene mainly arise from the strong coordination of the Fe-His93 bond.