The carotenoids are terpenoid fat-soluble pigments produced by plants, algae, and several bacteria and fungi. They are ubiquitous components of animal diets. Carotenoid cleavage oxygenase (CCO) superfamily members are involved in carotenoid metabolism and are present in all kingdoms of life. Throughout the animal kingdom, carotenoid oxygenases are widely distributed and they are completely absent only in two unicellular organisms, Monosiga and Leishmania. Mammals have three paralogs 15,15′-β-carotene oxygenase (BCO1), 9′,10′-β-carotene oxygenase (BCO2) and RPE65. The first two enzymes are classical carotenoid oxygenases: they cleave carbon‑carbon double bonds and incorporate two atoms of oxygen in the substrate at the site of cleavage. The third, RPE65, is an unusual family member, it is the retinoid isomerohydrolase in the visual cycle that converts all-trans-retinyl ester into 11-cis-retinol. Here we discuss evolutionary aspects of the carotenoid cleavage oxygenase superfamily and their enzymology to deduce what insight we can obtain from their evolutionary conservation.

类胡萝卜素是由植物、藻类和几种细菌和真菌产生的萜类脂溶性色素。它们是动物饮食中无处不在的成分。类胡萝卜素裂解加氧酶 (CCO) 超家族成员参与类胡萝卜素代谢，并存在于所有生命王国中。在整个动物界，类胡萝卜素加氧酶广泛分布，仅在两种单细胞生物Monosiga和Leishmania中完全不存在. 哺乳动物具有三个旁系同源物：15,15'-β-胡萝卜素加氧酶 (BCO1)、9',10'-β-胡萝卜素加氧酶 (BCO2) 和 RPE65。前两种酶是经典的类胡萝卜素加氧酶：它们切割碳-碳双键，并在切割位点的底物中加入两个氧原子。第三个，RPE65，是一个不寻常的家族成员，它是视觉循环中的类视黄醇异构水解酶，将全反式视黄酯转化为 11-顺式视黄醇。在这里，我们讨论类胡萝卜素裂解加氧酶超家族的进化方面及其酶学，以推断我们可以从它们的进化保守性中获得什么见解。