从超氧化物歧化酶的分布和结构看其分子进化

The Molecular Evolution of Superoxide Dismutase Based on its Distribution and Structure

超氧化物歧化酶（ＳＯＤ）是一种催化超氧化物阴离子自由基发生歧化反应，生成氧和过氧化氢的金属酶．按其结合的金属离子，区分为Ｆｅ－ＳＯＤ，Ｍｎ－ＳＯＤ和ＣｕＺｎ－ＳＯＤ三种．Ｆｅ－ＳＯＤ主要存在于原核细胞中；Ｍｎ－ＳＯＤ在原核和真核细胞中都存在；ＣｕＺｎ－ＳＯＤ主要存在于真核细胞中．Ｆｅ，Ｍｎ－ＳＯＤ的一级结构，空间结构及其性质很相似，来自一个共同的祖先；ＣｕＺｎ－ＳＯＤ的结构与前两者相差较大，是在以后的发展中单独进化的．

Superoxide dismutases (SODs) aremetal-containing enzymes that catalyze thedismutation of superoxide radicals to oxygen andhydrogen peroxide. Three classes of SODs,Fe-SOD, Mn-SOD and CuZn-SOD, have beendistinguished according to their bound metals.The Fe-SOD is essentially a prokaryotic enzyme,while the CuZn-SOD is essentially an eukaryoticenzyme. The Mn-SOD is present in bothprokaryotes and eukaryotes. The Fe- and MnSODs appear to highly similar in the primarystructure, three-dimensional structure and otherphysiochemical properties, but have no resemblance to CuZn-SOD. The Fe- and Mn-SOD canbe traced to a common ancestor, whereas CuZn-SOD has evolved independently at a later time.