作者:Fatbardha Varfaj、Siti N. A. Zulkifli、Hyoung-Goo Park、Victoria L. Challinor、James J. De Voss、Paul R. Ortiz de Montellano
DOI:10.1124/dmd.114.056903
日期:2014.5
Carbon-carbon bond cleavage reactions are catalyzed by, among others, lanosterol 14-demethylase (CYP51), cholesterol side-chain cleavage enzyme (CYP11), sterol 17 β -lyase (CYP17), and aromatase (CYP19). Because of the high substrate specificities of these enzymes and the complex nature of their substrates, these reactions have been difficult to characterize. A CYP1A2-catalyzed carbon-carbon bond cleavage reaction is required for conversion of the prodrug nabumetone to its active form, 6-methoxy-2-naphthylacetic acid (6-MNA). Despite worldwide use of nabumetone as an anti-inflammatory agent, the mechanism of its carbon-carbon bond cleavage reaction remains obscure. With the help of authentic synthetic standards, we report here that the reaction involves 3-hydroxylation, carbon-carbon cleavage to the aldehyde, and oxidation of the aldehyde to the acid, all catalyzed by CYP1A2 or, less effectively, by other P450 enzymes. The data indicate that the carbon-carbon bond cleavage is mediated by the ferric peroxo anion rather than the ferryl species in the P450 catalytic cycle. CYP1A2 also catalyzes O -demethylation and alcohol to ketone transformations of nabumetone and its analogs.
碳-碳键裂解反应主要由羊毛甾醇 14-脱甲基酶(CYP51)、胆固醇侧链裂解酶(CYP11)、甾醇 17 β-裂解酶(CYP17)和芳香化酶(CYP19)等催化。由于这些酶的底物特异性很高,而且底物性质复杂,因此这些反应一直难以表征。原药萘丁美酮转化为其活性形式 6-甲氧基-2-萘乙酸(6-MNA)需要 CYP1A2 催化的碳-碳键裂解反应。尽管萘丁美酮在全球范围内被用作消炎药,但其碳-碳键裂解反应的机理仍然模糊不清。在真实合成标准的帮助下,我们在此报告,该反应涉及 3-羟基化、碳-碳键裂解为醛,以及醛氧化为酸,所有反应均由 CYP1A2 催化,或由其他 P450 酶催化,但效果较差。数据表明,在 P450 催化循环中,碳-碳键的裂解是由过氧铁阴离子而非渡酰物种介导的。CYP1A2 还催化萘丁美酮及其类似物的 O-去甲基化和醇酮转化。