Why isn't 'standard' heme good enough for c-type and d1-type cytochromes?
Why isn't 'standard' heme good enough for c-type and d1-type cytochromes?
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DOI：
10.1039/b508139b
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发表时间：
2005-01-01
影响因子：
4
通讯作者：
Ferguson, SJ
中科院分区：
文献类型：
--
作者：
Allen, JWA;Barker, PD;Ferguson, SJ
这种观点旨在讨论为什么生物学经常修改的基本铁原卟啉IX部分，这是许多血红素蛋白质的非常通用的辅因子。一种非常常见的修饰是这种辅因子通过共价键连接到半胱氨酸残基侧链的两个（或很少一个）硫原子上。这种修饰导致c型细胞色素，其具有不同的结构和功能。根据细胞类型，共价键以不同的方式形成。有很少的理解的原因，这种复杂性的组装路线，但建议背后的共价修饰的理由。与广泛存在的c型细胞色素不同，d（1）血红素仅限于一种酶，即细胞色素cd（1）亚硝酸还原酶，它催化亚硝酸盐还原为一氧化氮的单电子还原。这是一种广泛衍生的血红素;与另一种类型的呼吸性亚硝酸盐还原酶进行比较，其中活性位点是c型血红素，但产物是氨。
This perspective seeks to discuss why biology often modifies the fundamental iron-protoporphyrin IX moiety that is the very versatile cofactor of many heme proteins. A very common modification is the attachment of this cofactor via covalent bonds to two ( or rarely one) sulfur atoms of cysteine residue side chains. This modification results in c-type cytochromes, which have diverse structures and functions. The covalent bonds are made in different ways depending on the cell type. There is little understanding of the reasons for this complexity in assembly routes but proposals for the rationale behind the covalentmodification are presented. In contrast to the widespread c-type cytochromes, the d(1) heme is restricted to a single enzyme, the cytochrome cd(1) nitrite reductase that catalyses the one-electron reduction of nitrite to nitric oxide. This is an extensively derivatised heme; a comparison is drawn with another type of respiratory nitrite reductase in which the active site is a c-type heme, but the product ammonia.