The Interaction of Porcine Dihydropyrimidine Dehydrogenase with the Chemotherapy Sensitizer: 5-Ethynyluracil
The Interaction of Porcine Dihydropyrimidine Dehydrogenase with the Chemotherapy Sensitizer: 5-Ethynyluracil
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猪二氢嘧啶脱氢酶与化疗增敏剂 5-乙炔尿嘧啶的相互作用
DOI：
10.1021/acs.biochem.1c00096
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发表时间：
2021
期刊：
影响因子：
2.9
通讯作者：
Moran, Graham R.
中科院分区：
文献类型：
--
作者：
Forouzesh, Dariush C.;Beaupre, Brett A.;Butrin, Arseniy;Wawrzak, Zdzislaw;Liu, Dali;Moran, Graham R.
二氢嘧啶脱氢酶 (DPD) 是一种复杂的酶，可还原嘧啶、尿嘧啶和胸腺嘧啶的 5,6-乙烯基键。 5-氟尿嘧啶 (5FU) 也是 DPD 的底物，也是用于治疗多种癌症的常见化疗剂。 5FU 还原为 5-氟-5,6-二氢尿嘧啶，消除了其毒性和功效。 DPD 活动水平高的患者在接受 5FU 治疗时通常预后较差。因此，DPD 是治疗多种癌症的核心缓解因素。 5-乙炔尿嘧啶 (5EU) 通过与嘧啶结合位点中的活性位点通用酸性半胱氨酸交联，共价灭活 DPD。该反应依赖于 5EU 和烟酰胺腺嘌呤二核苷酸磷酸 (NADPH) 的同时结合。这种三元复合物通过从 NADPH 中获取两个电子来诱导 DPD 被激活。 5EU 对 DPD 的共价失活与还原激活同时发生，速率常数为 ∼0.2 s–1。该动值与两种黄素辅因子之一的还原速率以及嘧啶活性位点中移动环的定位相关，该移动环将作为催化中的通用酸的半胱氨酸放置在靠近5EU乙炔基的位置。有效的交联依赖于酶的激活，但该过程似乎也具有构象方面，因为非还原性 NADPH 类似物也可以诱导部分失活。然后，交联通过切断在蛋白质上传输电子 56 Å 的质子耦合电子转移机制，使 DPD 失活。
Dihydropyrimidine dehydrogenase (DPD) is a complex enzyme that reduces the 5,6-vinylic bond of pyrimidines, uracil, and thymine. 5-Fluorouracil (5FU) is also a substrate for DPD and a common chemotherapeutic agent used to treat numerous cancers. The reduction of 5FU to 5-fluoro-5,6-dihydrouracil negates its toxicity and efficacy. Patients with high DPD activity levels typically have poor outcomes when treated with 5FU. DPD is thus a central mitigating factor in the treatment of a variety of cancers. 5-Ethynyluracil (5EU) covalently inactivates DPD by cross-linking with the active-site general acid cysteine in the pyrimidine binding site. This reaction is dependent on the simultaneous binding of 5EU and nicotinamide adenine dinucleotide phosphate (NADPH). This ternary complex induces DPD to become activated by taking up two electrons from the NADPH. The covalent inactivation of DPD by 5EU occurs concomitantly with this reductive activation with a rate constant of ∼0.2 s–1. Thiskinactvalue is correlated with the rate of reduction of one of the two flavin cofactors and the localization of a mobile loop in the pyrimidine active site that places the cysteine that serves as the general acid in catalysis proximal to the 5EU ethynyl group. Efficient cross-linking is reliant on enzyme activation, but this process appears to also have a conformational aspect in that nonreductive NADPH analogues can also induce a partial inactivation. Cross-linking then renders DPD inactive by severing the proton-coupled electron transfer mechanism that transmits electrons 56 Å across the protein.