Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, P.O. Box 30, 420111 Kazan, Russia.
Int J Mol Sci. 2021 Apr 29;22(9):4737. doi: 10.3390/ijms22094737.
The CYP74 clan cytochromes (P450) are key enzymes of oxidative metabolism of polyunsaturated fatty acids in plants, some Proteobacteria, brown and green algae, and Metazoa. The CYP74 enzymes, including the allene oxide synthases (AOSs), hydroperoxide lyases, divinyl ether synthases, and epoxyalcohol synthases (EASs) transform the fatty acid hydroperoxides to bioactive oxylipins. A novel CYP74 clan enzyme CYP440A18 of the Asian (Belcher's) lancelet (, Chordata) was biochemically characterized in the present work. The recombinant CYP440A18 enzyme was active towards all substrates used: linoleate and α-linolenate 9- and 13-hydroperoxides, as well as with eicosatetraenoate and eicosapentaenoate 15-hydroperoxides. The enzyme specifically converted α-linolenate 13-hydroperoxide (13-HPOT) to the oxiranyl carbinol (9,11,12,13,15)-11-hydroxy-12,13-epoxy-9,15-octadecadienoic acid (EAS product), α-ketol, 12-oxo-13-hydroxy-9,15-octadecadienoic acid (AOS product), and -12-oxo-10,15-phytodienoic acid (AOS product) at a ratio of around 35:5:1. Other hydroperoxides were converted by this enzyme to the analogous products. In contrast to other substrates, the 13-HPOT and 15-HPEPE yielded higher proportions of α-ketols, as well as the small amounts of cyclopentenones, -12-oxo-10,15-phytodienoic acid and its higher homologue, dihomo--12-oxo-3,6,10,15-phytotetraenoic acid, respectively. Thus, the CYP440A18 enzyme exhibited dual EAS/AOS activity. The obtained results allowed us to ascribe a name " EAS/AOS" (BbEAS/AOS) to this enzyme. BbEAS/AOS is a first CYP74 clan enzyme of Chordata species possessing AOS activity.
CYP74 族细胞色素（P450）是植物、一些变形菌、褐藻和绿藻以及后生动物多不饱和脂肪酸氧化代谢的关键酶。CYP74 酶，包括丙二烯氧化物合酶（AOS）、过氧化物裂解酶、二乙烯醚合酶和环氧化物醇合酶（EAS），将脂肪酸氢过氧化物转化为生物活性的氧代脂类。本工作对来自亚洲（贝尔彻氏）被囊动物（脊索动物）的新型 CYP74 族酶 CYP440A18 进行了生化特征描述。重组 CYP440A18 酶对所用的所有底物均具有活性：亚油酸和α-亚麻酸 9-和 13-氢过氧化物，以及二十碳四烯酸和二十碳五烯酸 15-氢过氧化物。该酶特异性地将α-亚麻酸 13-氢过氧化物（13-HPOT）转化为环氧化甲醇（9,11,12,13,15）-11-羟基-12,13-环氧-9,15-十八碳二烯酸（EAS 产物）、α-酮醇、12-氧代-13-羟基-9,15-十八碳二烯酸（AOS 产物）和-12-氧代-10,15-植二烯酸（AOS 产物），比例约为 35:5:1。该酶还将其他氢过氧化物转化为类似产物。与其他底物相比，13-HPOT 和 15-HPEPE 产生更多比例的α-酮醇，以及少量的环戊烯酮、-12-氧代-10,15-植二烯酸及其更高同系物，二氢-12-氧代-3,6,10,15-植物四烯酸。因此，CYP440A18 酶表现出双重 EAS/AOS 活性。获得的结果使我们能够将这种酶命名为“EAS/AOS”（BbEAS/AOS）。BbEAS/AOS 是第一个具有 AOS 活性的脊索动物 CYP74 族酶。
