Kikuchi Goro, Yoshida Tadashi, Noguchi Masato
Tohoku University School of Medicine, Sendai, Japan.
Biochem Biophys Res Commun. 2005 Dec 9;338(1):558-67. doi: 10.1016/j.bbrc.2005.08.020. Epub 2005 Aug 15.
The microsomal heme oxygenase system consists of heme oxygenase (HO) and NADPH-cytochrome P450 reductase, and plays a key role in the physiological catabolism of heme which yields biliverdin, carbon monoxide, and iron as the final products. Heme degradation proceeds essentially as a series of autocatalytic oxidation reactions involving heme bound to HO. Large amounts of HO proteins from human and rat can now be prepared in truncated soluble form, and the crystal structures of some HO proteins have been determined. These advances have greatly facilitated the understanding of the mechanisms of individual steps of the HO reaction. HO can be induced in animals by the administration of heme or several other substances; the induction is shown to involve Bach1, a translational repressor. The induced HO is assumed to have cytoprotective effects. An uninducible HO isozyme, HO-2, has been identified, so the authentic HO is now called HO-1. HOs are also widely distributed in invertebrates, higher plants, algae, and bacteria, and function in various ways according to the needs of individual species.
微粒体血红素加氧酶系统由血红素加氧酶（HO）和NADPH - 细胞色素P450还原酶组成，在血红素的生理分解代谢中起关键作用，最终产物为胆绿素、一氧化碳和铁。血红素降解基本上是一系列涉及与HO结合的血红素的自催化氧化反应。现在可以制备大量截短的可溶性形式的人和大鼠的HO蛋白，并且已经确定了一些HO蛋白的晶体结构。这些进展极大地促进了对HO反应各个步骤机制的理解。通过给予血红素或其他几种物质可以在动物中诱导HO；这种诱导显示涉及翻译阻遏物Bach1。诱导的HO被认为具有细胞保护作用。已经鉴定出一种不可诱导的HO同工酶HO - 2，因此真正的HO现在称为HO - 1。HO也广泛分布于无脊椎动物、高等植物、藻类和细菌中，并根据各个物种的需要以各种方式发挥作用。
