This review examines the current state of the art on the evolution of the families of Heme Copper Oxygen reductases (HCO) that oxidize cytochrome c and reduce oxygen to water, chiefly cytochrome oxidase, COX. COX is present in many bacterial and most eukaryotic lineages, but its origin has remained elusive. After examining previous proposals for COX evolution, the review summarizes recent insights suggesting that COX enzymes might have evolved in soil dwelling, probably iron-oxidizing bacteria which lived on emerged land over two billion years ago. These bacteria were the likely ancestors of extant acidophilic iron-oxidizers such as Acidithiobacillus spp., which belong to basal lineages of the phylum Proteobacteria. Proteobacteria may thus be considered the originators of COX, which was then laterally transferred to other prokaryotes. The taxonomy of bacteria is presented in relation to the current distribution of COX and C family oxidases, from which COX may have evolved.

这篇综述研究了血红素铜氧还原酶（HCO）家族进化的最新技术，该血红素铜氧化还原酶可氧化细胞色素c并将氧气还原为水，主要是细胞色素氧化酶COX。COX存在于许多细菌和大多数真核生物谱系中，但其起源仍然难以捉摸。在审查了先前关于COX进化的建议后，该综述总结了最近的见解，这些结论表明COX酶可能已经在土壤中进化，可能是二十亿年前生活在新兴土地上的铁氧化细菌。这些细菌是现存的嗜酸性铁氧化剂（如酸性硫杆菌属）的祖先，它们属于门的基础谱系。变形杆菌。因此，变形杆菌可以被认为是COX的起源，然后被横向转移到其他原核生物。细菌的分类法是与目前COX和C家族氧化酶的分布有关的，COX可能从中演化出来。