Catalytic and Inhibitory Mechanisms in Indoleamine 2,3-dioxygenase

吲哚胺 2,3-双加氧酶的催化和抑制机制

• 批准号: 7889844
• 负责人: Syun-Ru Yeh
• 金额: $ 35.22万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-01 至 2014-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7889844
• 关键词: Area; Attention; Binding; Chemistry; Clinical Trials; Comparative Study; Computing Methodologies; Cytochrome P450; Data; Development; Dioxygenases; Enzymes; Exhibits; Foundations; Freezing; Future; Goals; Heme; Human; Immunologic Surveillance; Immunosuppressive Agents; Intervention; Isomerism; Kinetics; Knowledge; Kynurenine; Link; Malignant Neoplasms; Mission; Mixed Function Oxygenases; Molecular; Mus; Mutagenesis; Names; Outcome; Oxygen; Pathway interactions; Pharmacologic Substance; Physiological; Physiology; Play; Positioning Attribute; Pre-Clinical Model; Property; Protein Isoforms; Public Health; Reaction; Recombinants; Reporting; Research; Role; Site; Solid; Spectroscopy, Fourier Transform Infrared; System; T-Lymphocyte; Techniques; Test Result; Testing; Tryptophan; Tryptophan 2,3 Dioxygenase; Work; X-Ray Crystallography; base; cancer cell; cancer therapy; cell mediated immune response; design; disability; evidence based guidelines; in vivo; indoleamine; inhibitor/antagonist; innovation; macrophage; methyl tryptophan; novel therapeutics; oxidation; programs; public health relevance; therapeutic target

DESCRIPTION (provided by applicant): Indoleamine 2,3-dioxygenase (IDO) catalyzes the oxidation of L-tryptophan to N-formyl kynurenine. In contrast to the wide spectrum of P450 monooxygenases, IDO is one of the only two heme-based dioxygenases in humans. Despite decades of effort, its dioxygenase mechanism remains elusive. IDO is an immunosuppressive enzyme, which plays an important role in allowing cancer cells to escape from immune surveillance. Recently, it has attracted a great deal of attention due to the recognition of its potential as a therapeutic target for cancer. Hence, there is a critical need for the delineation of the dioxygenase and inhibitory mechanisms of the two human isoforms of IDO, named hIDO1 and hIDO2. The long term goal of our program is (i) to define the molecular mechanism of heme-based dioxygenases, filling in the knowledge gap in heme oxygen chemistry, and (ii) to delineate the antitumor effect of IDO1/IDO2 inhibitors, aiding in the definition of IDO-linked cancer physiology. The objective of this application is to characterize the molecular properties of hIDO1 and hIDO2, in order to define their catalytic and inhibitory mechanisms. Our central hypothesis is that the catalytic and inhibitory mechanisms of the two IDO isoforms are distinct. The rationale is that the successful completion of this project will offer strong, conceptual and evidence-based guidelines for the development of IDO- targeted intervention against cancer. Thus, the proposed research is relevant to that part of NIH's mission that pertains to the development of fundamental knowledge that will potentially help to reduce the burdens of human disability. Guided by strong preliminary data, our hypothesis will be tested by the pursuit of two specific aims: (i) define the dioxygenase mechanisms of hIDO1 and hIDO2, and (ii) identify the inhibition mechanisms of hIDO1 and hIDO2. To achieve our objective we will employ a multi-faceted approach with a complementary set of spectroscopic techniques (Raman, UV-Vis, FTIR, EPR, MS and X-ray crystallography), combined with computational methodologies (MD and QM/MM) and mutagenesis. The proposed project is innovative because (i) the availability of both hIDO1 and hIDO2 places us in a unique position for carrying out the proposed comparative studies, and (ii) the unique fast-mixing/freeze-quenching techniques developed in our lab enable effective structural characterization of key enzymatic intermediates that are inaccessible in other labs. The proposed research is significant because the successful completion of this project will lay a solid foundation for the future design of novel therapeutic strategies targeting IDO, as well as to advance fundamental understanding of heme-based dioxygenase chemistry. PUBLIC HEALTH RELEVANCE: The proposed studies are focused on an important, but poorly understood, area of research dealing with two isoforms of indoleamine 2,3-dioxygenase, which play an essential role in allowing cancer cells to escape from immune surveillance. The proposed research is relevant to public health, because a detailed understanding of catalytic and inhibitory mechanisms of the two isoforms of the enzyme should provide a foundation for the development of their inhibitors for pharmaceutical intervention against cancer.

描述（申请人提供）：吲哚胺2,3-双加氧酶（IDO）催化L-色氨酸氧化成N-甲酰犬尿氨酸。与广谱 P450 单加氧酶相比，IDO 是人类仅有的两种基于血红素的双加氧酶之一。尽管经过数十年的努力，其双加氧酶机制仍然难以捉摸。 IDO 是一种免疫抑制酶，在让癌细胞逃避免疫监视方面发挥着重要作用。最近，由于认识到其作为癌症治疗靶点的潜力，它引起了广泛的关注。因此，迫切需要描述两种人类 IDO 亚型（hIDO1 和 hIDO2）的双加氧酶和抑制机制。我们计划的长期目标是 (i) 定义基于血红素的双加氧酶的分子机制，填补血红素氧化学的知识空白，以及 (ii) 描述 IDO1/IDO2 抑制剂的抗肿瘤作用，帮助IDO 相关癌症生理学的定义。本应用的目的是表征 hIDO1 和 hIDO2 的分子特性，以确定它们的催化和抑制机制。我们的中心假设是两种 IDO 亚型的催化和抑制机制是不同的。理由是，该项目的成功完成将为开发 IDO 靶向癌症干预措施提供强有力的、概念性的和基于证据的指南。因此，拟议的研究与 NIH 使命的一部分相关，该使命涉及基础知识的发展，这将有可能有助于减轻人类残疾的负担。在强有力的初步数据的指导下，我们的假设将通过追求两个具体目标来检验：(i) 定义 hIDO1 和 hIDO2 的双加氧酶机制，以及 (ii) 确定 hIDO1 和 hIDO2 的抑制机制。为了实现我们的目标，我们将采用多方面的方法和一套互补的光谱技术（拉曼、紫外-可见、FTIR、EPR、MS 和 X 射线晶体学），并结合计算方法（MD 和 QM/MM）和诱变。拟议的项目具有创新性，因为 (i) hIDO1 和 hIDO2 的可用性使我们处于开展拟议比较研究的独特位置，以及 (ii) 我们实验室开发的独特快速混合/冷冻淬灭技术能够有效地其他实验室无法获得的关键酶中间体的结构表征。拟议的研究意义重大，因为该项目的成功完成将为未来设计针对 IDO 的新型治疗策略奠定坚实的基础，并促进对基于血红素的双加氧酶化学的基本理解。 公共健康相关性：拟议的研究重点关注一个重要但知之甚少的研究领域，该领域涉及吲哚胺 2,3-双加氧酶的两种亚型，它们在让癌细胞逃避免疫监视方面发挥着重要作用。拟议的研究与公共卫生相关，因为详细了解酶的两种亚型的催化和抑制机制应该为开发其抑制剂用于抗癌药物干预奠定基础。