Terminal steps of haem biosynthesis
Terminal steps of haem biosynthesis
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DOI：
10.1042/bst0300590
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发表时间：
2002-08-01
影响因子：
3.9
通讯作者：
Dailey, HA
中科院分区：
文献类型：
--
作者：
Dailey, HA
血红素生物合成的最后三个步骤是粪卟啉原III氧化脱羧为原卟啉原IX，然后是原卟啉原的六电子氧化为原卟啉IX，最后是亚铁的插入形成血红素。有趣的是，与厌氧生物相比，自然界已经进化出不同的酶机制来处理好氧生物的倒数第二步（粪卟啉原氧化酶）和倒数第二步（原卟啉原氧化酶）。最后一步由亚铁螯合酶催化。这种酶显然是保守的一小部分基本的催化残基，但变化，显着的大小，亚基组成，细胞位置和存在或不存在的[2Fe-2S]簇。综述了粪卟啉原氧化酶和原卟啉原氧化酶的酶学性质和物理性质。铁螯合酶是这三种酶中最具特征的酶，将特别强调从枯草芽孢杆菌和人类酶的晶体结构中所了解到的。
The terminal three steps in haem biosynthesis are the oxidative decarboxylation of coproporphyrinogen III to protoporphyrinogen IX, followed by the six-electron oxidation of protoporphyrinogen to protoporphyrin IX, and finally the insertion of ferrous iron to form haem. Interestingly, Nature has evolved distinct enzymic machinery to deal with the antepenultimate (coproporphyrinogen oxidase) and penultimate (protoporphyrinogen oxidase) steps for aerobic compared with anaerobic organisms. The terminal step is catalysed by the enzyme ferrochelatase. This enzyme is clearly conserved with regard to a small set of essential catalytic residues, but varies, significantly with regard to size, subunit composition, cellular location and the presence or absence of a [2Fe-2S] cluster. Coproporphyrinogen oxidase and protoporphyrinogen oxidase are reviewed with regard to their enzymic and physical characteristics. Ferrochelatase, which is the best characterized of these three enzymes, will be described with particular emphasis paid to what has been learned from the crystal structure of the Bacillus subtilis and human enzymes.