Miyahisa Ikuo, Suzuki Hideo, Mizukami Atsushi, Tanaka Yukiya, Ono Midori, Hixon Mark S, Matsui Junji
Pharmaceutical Research Division, Takeda Pharmaceutical Company Ltd. , 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan.
Takeda California Inc. , 10410 Science Center Drive, San Diego, California 92121, United States.
ACS Med Chem Lett. 2016 Aug 10;7(9):868-72. doi: 10.1021/acsmedchemlett.6b00241. eCollection 2016 Sep 8.
Delta-5 desaturase (D5D) catalyzes the conversion from dihomo-gamma linoleic acid (DGLA) to arachidonic acid (AA). DGLA and AA are common precursors of anti- and pro-inflammatory eicosanoids, respectively, making D5D an attractive drug target for inflammatory-related diseases. Despite several reports on D5D inhibitors, their biochemical mechanisms of action (MOAs) remain poorly understood, primarily due to the difficulty in performing quantitative enzymatic analysis. Herein, we report a radioligand binding assay to overcome this challenge and characterized T-3364366, a thienopyrimidinone D5D inhibitor, by use of the assay. T-3364366 is a reversible, slow-binding inhibitor with a dissociation half-life in excess of 2.0 h. The long residence time was confirmed in cellular washout assays. Domain swapping experiments between D5D and D6D support [(3)H]T-3364366 binding to the desaturase domain of D5D. The present study is the first to demonstrate biochemical MOA of desaturase inhibitors, providing important insight into drug discovery of desaturase enzymes.
Δ5去饱和酶（D5D）催化二高-γ-亚麻酸（DGLA）向花生四烯酸（AA）的转化。DGLA和AA分别是抗炎和促炎类二十烷酸的常见前体，这使得D5D成为炎性相关疾病一个有吸引力的药物靶点。尽管有几篇关于D5D抑制剂的报道，但其生化作用机制（MOA）仍知之甚少，主要是因为进行定量酶分析存在困难。在此，我们报道一种放射性配体结合测定法以克服这一挑战，并使用该测定法对噻吩并嘧啶酮类D5D抑制剂T-3364366进行了表征。T-3364366是一种可逆的慢结合抑制剂，解离半衰期超过2.0小时。在细胞洗脱试验中证实了其较长的停留时间。D5D和D6D之间的结构域交换实验支持[³H]T-3364366与D5D的去饱和酶结构域结合。本研究首次证明了去饱和酶抑制剂的生化作用机制，为去饱和酶类药物的发现提供了重要见解。
