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.

项目概要 人色氨酸双加氧酶 (hTDO) 和吲哚胺 2, 3-双加氧酶 1 (hIDO1) 是两种血红素蛋白 催化 L-色氨酸 (Trp) 生成 N-甲酰犬尿氨酸的双氧化反应。虽然它是 人们普遍认为，电子和质子对于血红素蛋白的氧活化至关重要， 双加氧酶非常独特，可以催化色氨酸的氧化环裂解反应而不消耗 任何电子或质子。时间分辨共振拉曼光谱，结合 QM/MM 通过模拟，我们建立了一种底物辅助机制来解释不寻常的化学反应 由双加氧酶催化。最近，我们发现，除了色氨酸双氧合活性之外， 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， 将活性全蛋白转化为非活性脱辅基蛋白，(ii) 氧化酶反应，将 O2 还原为 超氧化物，以及 (iii) 过氧化物酶反应，将 H2O2 还原为水。虽然 hTDO 和 hIDO1 共享 共同的活性位点结构，并以相同的机制 hIDO1 催化色氨酸双氧化反应 不表现出 H2O2 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 研究结果扩展了基于血红素的双加氧酶的底物组合和催化能力。主要 该项目的目标是破译决定这两种酶活性的结构决定因素 双加氧酶。该项目的科学前提是理解新的酶活性 hTDO 和 hIDO1 的研究将加深我们对血红素氧化学的了解，并为它们提供新的见解 生理功能，从而为疾病控制和预防提供指导。