Expanding the Catalytic Repertoire of Heme-based Dioxygenases

扩展血红素双加氧酶的催化能力

• 批准号: 10719622
• 负责人: Syun-Ru Yeh
• 金额: $ 38.64万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-15 至 2027-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10719622
• 关键词: Accounting; Active Sites; Apoproteins; Binding; Biological Assay; Chemicals; Chemistry; Collaborations; Communication; Comprehension; Consumption; Coupled; Cytochrome P450; Data; Dioxygenases; Disease; Distal; Drug Targeting; Electron Transport; Electrons; Electrostatics; Environment; Flavin Mononucleotide; Goals; Guidelines; Health; Heme; Hemeproteins; Histidine; Human; Human Activities; Hydrogen Peroxide; Kinetics; Knowledge; Kynurenine; Learning; Malignant Neoplasms; Mass Spectrum Analysis; Mediator; Mutagenesis; Oxidases; Oxygen; Oxygenases; Peroxidases; Physiological; Process; Property; Proteins; Protons; Public Health; Raman Spectrum Analysis; Reaction; Research; Serine; Solvents; Spectrum Analysis; Structure; Superoxides; Techniques; Testing; Therapeutic; Time; Tryptophan; Tryptophan 2,3 Dioxygenase; Water; Work; X-Ray Crystallography; absorption; disorder control; disorder prevention; experimental study; heme a; human disease; insight; molecular dynamics; novel; pressure; programs; simulation; structural determinants

PROJECT SUMMARY Human tryptophan dioxygenase (hTDO) and indoleamine 2, 3-dioxygenase 1 (hIDO1) are two hemeproteins that catalyze the dioxygenation reaction of L-tryptophan (Trp) to N-formyl kynurenine. Although it is generally believed that electrons and protons are crucial for oxygen activation by hemeproteins, the dioxygenases are so unique that they catalyze the oxidative ring cleavage reaction of Trp without consuming any electrons or protons. With time-resolved resonance Raman spectroscopy, combined with QM/MM simulations, we have established a substrate-assisted mechanism accounting for the unusual chemistry catalyzed by the dioxygenases. Recently, we discovered that, in addition to the Trp dioxygenation activity, hTDO can bind NAD(P)H in the active site, thereby repurposing it for (i) a heme oxygenase (HO) reaction, which converts the active holoprotein to the inactive apoprotein, (ii) an oxidase reaction, which reduces O2 to superoxide, and (iii) a peroxidase reaction, which reduces H2O2 to water. Although hTDO and hIDO1 share a common active site structure and catalyze the Trp dioxygenation reaction with the same mechanism, hIDO1 does not exhibit the HO activity, but it retains the oxidase and peroxidase activities. These exciting new findings expand the substrate portfolio and the catalytic repertoire of the heme-based dioxygenases. The major goal of this project is to decipher the structural determinants dictating the novel enzymatic activities of the two dioxygenases. The scientific premise of this project is that the comprehension of the new enzymatic activities of hTDO and hIDO1 will further our knowledge in heme oxygen chemistry and provide new insights into their physiological functions, thereby offering guidelines for disease control and prevention.

项目摘要 人色氨酸双加氧酶（hTDO）和吲哚胺2，3-双加氧酶1（hIDO 1）是两种血红素蛋白 其催化L-色氨酸（Trp）至N-甲酰基犬尿氨酸的二氧化反应。虽然 一般认为电子和质子对于血红素蛋白的氧活化是至关重要的， 双加氧酶是如此独特，以至于它们催化Trp的氧化环裂解反应而不消耗 任何电子或质子。利用时间分辨共振拉曼光谱，结合QM/MM 模拟，我们已经建立了一个基板辅助机制占不寻常的化学 由双加氧酶催化最近，我们发现，除了色氨酸双氧化活性， hTDO可以在活性位点结合NAD（P）H，从而将其重新用于（i）血红素加氧酶（HO）反应， 其将活性全蛋白转化为非活性脱辅基蛋白，（ii）氧化酶反应，其将O2还原为 过氧化物，和（iii）过氧化物酶反应，其将H2 O2还原成水。虽然hTDO和hIDO 1共享 一个共同的活性中心结构，并以相同的机理催化色氨酸双加氧反应，hIDO 1 不显示HO活性，但保留了氧化酶和过氧化物酶活性。这些令人兴奋的新 研究结果扩大了底物组合和血红素为基础的双加氧酶的催化库。主要 该项目的目标是破译决定这两种酶的新酶活性的结构决定因素。 双加氧酶本课题的科学前提是对新酶活性的理解 hTDO和hIDO 1的研究将进一步加深我们在血红素氧化学方面的知识，并为它们的生物学特性提供新的见解。 生理功能，从而为疾病控制和预防提供指导。