Blue myoglobin reconstituted with an iron porphycene shows extremely high oxygen affinity
Blue myoglobin reconstituted with an iron porphycene shows extremely high oxygen affinity
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DOI：
10.1021/ja0265052
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发表时间：
2002-09-25
影响因子：
15
通讯作者：
Hisaeda, Y
中科院分区：
文献类型：
--
作者：
Hayashi, T;Dejima, H;Hisaeda, Y
肌红蛋白将是一个很好的支架工程蛋白质的功能。为了调节肌红蛋白的生理功能，几乎所有的方法都是通过定点突变来实现的，然而，很少有研究表明肌红蛋白的功能有显著的改善。相比之下，我们专注于用人工辅基取代蛋白质中的血红素。最近，我们制备了一种新的肌红蛋白重构与铁卟啉作为结构异构体的mesoheme。蓝色的重组肌红蛋白相对稳定，脱氧肌红蛋白可逆地结合配体。有趣的是，重组肌红蛋白的O2亲和力为1.1 × 109 M-1，比天然肌红蛋白高出1,400倍。此外，不利的自氧化动力学显示重构肌红蛋白相对于天然肌红蛋白的速率降低7倍，表明稳定的氧形式对抗自氧化。净结果来自于重组肌红蛋白中O2配体的缓慢解离，koff= 0.11 s-1，这是由于His 64和带负电荷的分子氧之间形成强氢键。目前的研究表明，天然血红素与人工创建的辅基的替代将给我们一个独特的功能成为血红素蛋白。
Myoglobin will be a good scaffold for engineering a function into proteins. To modulate the physiological function of myoglobin, almost all approaches have been demonstrated by site-directed mutagenesis, however, there are few studies which show a significant improvement in the function. In contrast, we focused on the replacement of heme in the protein with an artificial prosthetic group. Recently, we prepared a novel myoglobin reconstituted with an iron porphycene as a structural isomer of mesoheme. The bluish colored reconstituted myoglobin is relatively stable and the deoxymyoglobin reversibly binds ligands. Interestingly, the O2affinity of the reconstituted myoglobin, 1.1 × 109M-1, is a significant 1,400-fold higher than that of the native myoglobin. Furthermore, the unfavorable autoxidation kinetics show 7-fold decrease in rate for the reconstituted myoglobin relative to the native myoglobin, indicating the stable oxy-form against autoxidation. The net results come from the slow dissociation of the O2ligand in the reconstituted myoglobin,koff= 0.11 s-1, because of the formation of strong hydrogen bond between His64 and negatively charged dioxygen. The present study indicates that the replacement of native heme with an artificially created prosthetic group will give us a unique function into a hemoprotein.