Booker Squire J, Grove Tyler L
F1000 Biol Rep. 2010 Jul 14;2:52. doi: 10.3410/B2-52.
Enzymes of the radical SAM (RS) superfamily catalyze a diverse assortment of reactions that proceed via intermediates containing unpaired electrons. The radical initiator is the common metabolite S-adenosyl-l-methionine (SAM), which is reductively cleaved to generate a 5'-deoxyadenosyl 5'-radical, a universal and obligate intermediate among enzymes within this class. A bioinformatics study that appeared in 2001 indicated that this superfamily contained over 600 members, many catalyzing reactions that were rich in novel chemical transformations. Since that seminal study, the RS superfamily has grown immensely, and new details about the scope of reactions and biochemical pathways in which its members participate have emerged. This review will highlight only a few of the most significant findings from the past 2-3 years, focusing primarily on: RS enzymes involved in complex metallocofactor maturation; characterized RS enzymes that lack the canonical CxxxCxxC motif; RS enzymes containing multiple iron-sulfur clusters; RS enzymes catalyzing reactions with compelling medical implications; and the energetics and mechanism of generating the 5'-deoxyadenosyl radical. A number of significant studies of RS enzymes will unfortunately be omitted, and it is hoped that the reader will access the relevant literature - particularly a number of superb review articles recently written on the subject - to acquire a deeper appreciation of this class of enzymes.
自由基S-腺苷甲硫氨酸（RS）超家族的酶催化各种各样的反应，这些反应通过含有未成对电子的中间体进行。自由基引发剂是常见的代谢物S-腺苷-L-甲硫氨酸（SAM），它被还原裂解生成5'-脱氧腺苷5'-自由基，这是该类酶中普遍且必不可少的中间体。2001年发表的一项生物信息学研究表明，这个超家族包含600多个成员，许多成员催化的反应富含新颖的化学转化。自那项开创性研究以来，RS超家族已大幅扩展，其成员参与的反应范围和生化途径的新细节也已出现。本综述将仅突出过去两到三年中一些最重要的发现，主要关注：参与复杂金属辅因子成熟的RS酶；缺乏典型CxxxCxxC基序的已表征RS酶；含有多个铁硫簇的RS酶；催化具有重要医学意义反应的RS酶；以及生成5'-脱氧腺苷自由基的能量学和机制。不幸的是，将省略一些关于RS酶的重要研究，希望读者查阅相关文献——特别是最近撰写的一些关于该主题的优秀综述文章——以更深入地了解这类酶。
