Meininger David, Zalameda Leeanne, Liu Yichin, Stepan Lara P, Borges Luis, McCarter John D, Sutherland Claire L
Protein Sciences, Amgen Inc., Seattle, WA 98119, USA.
Biochim Biophys Acta. 2011 Dec;1814(12):1947-54. doi: 10.1016/j.bbapap.2011.07.023. Epub 2011 Jul 31.
Indoleamine 2,3-dioxygenase (IDO1) catalyzes the first step in tryptophan breakdown along the kynurenine pathway. Therapeutic inhibition of IDO1 is receiving much attention due to its proposed role in the pathogenesis of several diseases including cancer, hypotension and neurodegenerative disorders. A related enzyme, IDO2 has recently been described. We report the first purification and kinetic characterization of human IDO2 using a facile l-tryptophan consumption assay amenable to high throughput screening. We found that the K(m) of human IDO2 for l-tryptophan is much higher than that of IDO1. We also describe the identification and characterization of a new IDO1 inhibitor compound, Amg-1, by high throughput screening, and compare the inhibition profiles of IDO1 and IDO2 with Amg-1 and previously described compounds. Our data indicate that human IDO1 and IDO2 have different kinetic parameters and different inhibition profiles. Docking of Amg-1 and related analogs to the known structure of IDO1 and to homology-modeled IDO2 suggests possible rationales for the different inhibition profiles of IDO1 and IDO2.
吲哚胺2,3-双加氧酶（IDO1）催化色氨酸沿犬尿氨酸途径分解代谢的第一步。由于IDO1在包括癌症、低血压和神经退行性疾病在内的多种疾病发病机制中所起的作用，对其进行治疗性抑制受到了广泛关注。最近发现了一种相关酶，即IDO2。我们报告了首次使用适用于高通量筛选的简易L-色氨酸消耗试验对人IDO2进行纯化和动力学表征。我们发现人IDO2对L-色氨酸的米氏常数（K(m)）远高于IDO1。我们还描述了通过高通量筛选鉴定和表征一种新型IDO1抑制剂化合物Amg-1，并比较了Amg-1与先前描述的化合物对IDO1和IDO2的抑制谱。我们的数据表明，人IDO1和IDO2具有不同的动力学参数和不同的抑制谱。将Amg-1及相关类似物与IDO1的已知结构和同源建模的IDO2进行对接，揭示了IDO1和IDO2不同抑制谱的可能原因。
