Role of heme types in heme-copper oxidases: effects of replacing a heme b with a heme o mimic in an engineered heme-copper center in myoglobin.
Role of heme types in heme-copper oxidases: effects of replacing a heme b with a heme o mimic in an engineered heme-copper center in myoglobin.
复制标题
血红素类型在血红素铜氧化酶中的作用：在肌红蛋白的工程血红素铜中心中用血红素 o 模拟物取代血红素 b 的效果。
DOI：
10.1021/ja052659g
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Lu,Yi
中科院分区：
文献类型：
--
作者：
Wang,Ningyan;Zhao,Xuan;Lu,Yi
To address the role of the secondary hydroxyl group of hemea/oin heme-copper oxidases, we incorporated Fe(III)-2,4 (4,2) hydroxyethyl vinyl deuterioporphyrin IX, as a hemeomimic, into the engineered heme-copper center in myoglobin (sperm whale myoglobin L29H/F43H, called CuBMb). The only difference between the hemebof myoglobin and the hemeomimic is the substitution of one of the vinyl side chains of the former with a hydroxyethyl group of the latter. This substitution resulted in an ∼4 nm blue shift in the Soret band and ∼20 mV decrease in the heme reduction potential. In a control experiment, the hemebin CuBMb was also replaced with a mesoheme, which resulted in an ∼13 nm blue shift and ∼30 mV decrease in the heme reduction potential. Kinetic studies of the hemeomimic-substituted CuBMb showed significantly different reactivity toward copper-dependent oxygen reduction from that of theb-type CuBMb. In reaction with O2, CuBMb with a native hemebshowed heme oxygenase activity by generating verdoheme in the presence of Cu(I). This heme degradation reaction was slowed by ∼19-fold in the hemeomimic-substituted CuBMb (from 0.028 s-1to 0.0015 s-1), while the mesoheme-substituted CuBMb shared a similar heme degradation rate with that of CuBMb (0.023 s-1). No correlation was found between the heme reduction potential and its O2reactivity. These results strongly suggest the critical role of the hydroxyl group of hemeoin modulating heme-copper oxidase activity through participation in an extra hydrogen-bonding network.
