Sevoz C, Benoit E, Buronfosse T
Unité Associée DGER-INRA "Toxicologie et Métabolisme Comparés des Xénobiotiques", Ecole Nationale Vétérinaire de Lyon, Marcy l'Etoile, France.
Drug Metab Dispos. 2000 Apr;28(4):398-402.
2-Arylpropionic acids are a class of frequently used nonsteroidal anti-inflammatory drugs exhibiting a potent inhibition of cyclooxygenase isoforms supported by the (+)S-enantiomer alone. Nevertheless, some of these compounds in the (-)R configuration may undergo extensive inversion of configuration to their antipode. The key molecular basis for this mechanism invokes the stereoselective formation of the coenzyme A (CoA) thioester of the 2-arylpropionic acid by long-chain acyl-CoA synthetases (ACSs). In this report, rat recombinant ACS1 and ACS2 enzymes, constitutively highly expressed in adult rat liver and brain, respectively, have been overproduced in Escherichia coli strains and purified to homogeneity to investigate the involvement of these enzymes in the thioesterification of fenoprofen and ibuprofen. Recombinant ACS1 efficiently catalyzed both nonsteroidal anti-inflammatory drugs with Michaelis-Menten parameters of K(M) = 1686 +/- 93 microM, V(max) = 353 +/- 45 nmol/min/mg protein for (-)R-ibuprofen and K(M) = 103 +/- 12 microM, V(max) = 267 +/- 10 nmol/min/mg protein for (-)R-fenoprofen, and exhibited a marked stereoselectivity in favor of the (-)R-enantiomer. Recombinant ACS2, a closely related sequence with ACS1, exhibited a lower enzymatic efficacy from 7- to 130-fold for (-)R-ibuprofen and (-)R-fenoprofen, respectively. On the basis of these findings and considering the level of tissue expression of the different long-chain ACSs, ACS1 appears to be the major enzyme involved in the first step of the chiral inversion of 2-arylpropionic acids. Nevertheless, the participation of other ACS isoforms of minor quantitative importance could not be excluded in the thioesterification of xenobiotics.
2-芳基丙酸是一类常用的非甾体抗炎药，仅由(+)S-对映体就能对环氧化酶同工型产生强效抑制作用。然而，一些呈(-)R构型的此类化合物可能会发生广泛的构型翻转，转变为其对映体。这种机制的关键分子基础是长链酰基辅酶A合成酶（ACSs）对2-芳基丙酸辅酶A（CoA）硫酯的立体选择性形成。在本报告中，分别在成年大鼠肝脏和大脑中组成性高表达的大鼠重组ACS1和ACS2酶，已在大肠杆菌菌株中过量表达并纯化至同质，以研究这些酶在非诺洛芬和布洛芬硫酯化反应中的作用。重组ACS1能有效催化这两种非甾体抗炎药，对于(-)R-布洛芬，米氏参数为K(M)=1686±93微摩尔，V(max)=353±45纳摩尔/分钟/毫克蛋白质；对于(-)R-非诺洛芬，K(M)=103±12微摩尔，V(max)=267±10纳摩尔/分钟/毫克蛋白质，并且对(-)R-对映体表现出明显的立体选择性。重组ACS2与ACS1序列密切相关，对(-)R-布洛芬和(-)R-非诺洛芬的酶活性分别低7至130倍。基于这些发现，并考虑到不同长链ACSs的组织表达水平，ACS1似乎是参与2-芳基丙酸手性翻转第一步的主要酶。然而，在异生素硫酯化反应中，不能排除其他数量上不太重要的ACS同工型的参与。
