Binding of Mammalian and Avian Ferritins with Biotinylated Hemin: Demonstration of Preferential Binding of the H Subunit to Heme
Binding of Mammalian and Avian Ferritins with Biotinylated Hemin: Demonstration of Preferential Binding of the H Subunit to Heme
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DOI：
10.1292/jvms.10-0375
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发表时间：
2011-03-01
影响因子：
1.2
通讯作者：
Orino, Koichi
中科院分区：
文献类型：
--
作者：
Nakai, Miki;Murata, Naomi;Orino, Koichi
铁蛋白与血红素的结合已经用商品马脾铁蛋白进行了很好的研究，铁蛋白几乎完全由L亚基组成，这表明哺乳动物铁蛋白与血红素结合。本研究表明，哺乳动物全铁蛋白（商品马脾铁蛋白和纯化马脾、牛脾和犬肝铁蛋白，L/H亚基比分别为4.0、1.1和2.3）及其载铁蛋白结合的生物素化血红蛋白；载铁蛋白的结合活性高于全铁蛋白，但犬的载铁蛋白与全铁蛋白的结合活性相同。杆状病毒表达系统表达的牛铁蛋白H亚基均聚物与血红素结合，与生物素化血红素的结合活性高于同一系统表达的L亚基均聚物。这些结合被血红素抑制，而不含铁或zn -原卟啉IX （Zn-PPIX）不受抑制。纯化的鸡肝全铁蛋白仅由H亚基组成，与哺乳动物全铁蛋白相比，与生物素化血红蛋白的结合活性最高。血红素也能抑制鸡肝全铁蛋白与生物素化血红素的结合，而PPIX和Zn-PPIX则不能。这些结果表明，哺乳动物和鸟类铁蛋白结合血红素和H亚基优先识别血红素。
The binding of ferritin to heme has been well studied using commercial horse spleen apoferritin, which is almost entirely composed of the L subunit, suggesting that mammalian ferritins bind heme. The present study revealed that both mammalian holoferritins (commercial horse spleen ferritin and purified horse spleen, bovine spleen and canine liver ferritins with L/H subunit ratios of 4.0, 1.1, and 2.3, respectively) and their apoferritins bound biotinylated hemin; apoferritins had higher binding activity than holoferritins, except for canine holo- and apoferritins, which showed the same binding. Bovine ferritin H subunit homopolymers expressed by a baculovirus expression system showed heme binding and had higher binding activity to biotinylated hemin than the L subunit homopolymer expressed by the same system. These bindings were inhibited by heme but not by iron-free or Zn-protoporphyrin IX (Zn-PPIX). Purified chicken liver holoferritin was found to be composed of only H subunits and showed the highest binding activity with biotinylated hemin compared with mammalian holoferritins. The binding of chicken liver holoferritin to biotinylated hemin was also inhibited by heme but not by PPIX or Zn-PPIX. These results indicate that mammalian and avian ferritins bind heme and that the H subunit preferentially recognizes heme.