Flavins as Carbon Transfer Agents in Enzymology

黄素作为酶学中的碳转移剂

• 批准号: 1905267
• 负责人: Bruce Palfey
• 金额: $ 48万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-10-01 至 2023-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1905267&HistoricalAwards=false
• 关键词: Flavins; Carbon; Transfer; Agents; Enzymology

Flavins are derivatives of vitamin b2 that have long been known to help enzymes move electrons in biological reactions. Interestingly, it is now becoming apparent that flavins can sometimes serve as carbon-carriers. With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Dr. Bruce Palfey, University of Michigan, to investigate this newly recognized and not well understood type of reaction of flavins. This work is focusing on the way the protein thymidylate synthase controls the transfer and modification of a single carbon atom in an important biochemical reaction that is needed for DNA synthesis. A large number of bacteria use this type of reaction in the pathway to synthesize their DNA, so this project is elucidating a fundamental chemical process that is widespread but poorly understood. The project draws on a variety of chemical methods, some involving advanced technologies that allow very fast processes to be observed. The participants in the project, such as undergraduates and postdoctoral fellows, are receiving training in a unique blend of interdisciplinary scientific techniques, strengthening the capabilities of our technical workforce.Flavin enzyme-chemistry is now extending well beyond the canonical borders set by reduction and oxidation using the transfer of hydride equivalents, thiol/disulfide interchanges, single-electron transfers, and reactions with O2. Among the surprising new findings are enzymes that make iminium adducts with reduced flavins. These iminium adducts undergo a variety of fates depending on the particular enzyme. A flavin-dependent thymidylate synthase (thyX) forms thymine using a methylene derived from methylenetetrahydrofolate (CH2THF) and reducing equivalents derived from pyridine nucleotide. Recent evidence implicates the reduced flavin-iminium adduct as the carbon-transfer agent. Key reactive intermediates are being trapped and their chemical structures are being determined by NMR spectroscopy. Synthetic flavins are being used to learn about key transition states from linear free energy relationships and to gain insight into factors that favor carbon-transfer over possibly competitive hydride transfer. Proton transfers, which must be critical in controlling the transfer of electrophilic carbon, are being studied in detail by transient kinetics in the carbon-transfer route leading to thymidylate. Taken as a whole, this project is defining the catalytic strategies and challenges that many enzymes are now recognized to face.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

黄素是维生素B2的衍生物，长期以来已知可以帮助酶在生物反应中移动电子。有趣的是，现在很明显，黄素有时可以用作碳载体。通过该奖项，化学部门的化学过程计划正在为密歇根大学的布鲁斯·帕尔菲（Bruce Palfey）博士提供资金，以调查这种新认可且对黄素的反应类型不充分。这项工作的重点是蛋白质胸苷酸合酶控制DNA合成所需的重要生化反应中单个碳原子的转移和修饰。大量细菌在合成其DNA的途径中使用了这种类型的反应，因此该项目正在阐明一种基本的化学过程，该过程是广泛但知之甚少的。该项目利用了多种化学方法，其中一些涉及高级技术，这些技术可以观察到非常快速的过程。该项目的参与者，例如本科生和博士后研究员，正在接受独特的跨学科科学技术融合的培训，增强了我们技术人员的能力。Flavin酶化学的能力现在，使用单层式互动式的固定剂，通过均匀的氧化剂，远远超出了均超出范围的范围。转移和与O2的反应。令人惊讶的新发现之一是使黄素减少的亚米属加合物的酶。这些亚米合并会根据特定酶而经历多种命运。黄素依赖性的胸苷合酶（thyx）使用源自甲基四氢叶酸（CH2THF）的亚甲基形成胸腺嘧啶，并减少源自吡啶核苷酸的等效物。最近的证据表明，黄素 - 富加合物作为碳转移剂的降低。关键的反应性中间体被困在NMR光谱法确定其化学结构。合成黄素被用来从线性自由能关系中学习关键过渡状态，并深入了解有利于碳转移而不是可能具有竞争力的氢化物转移的因素。质子转移对于控制亲电碳的转移至关重要的质子转移正在通过临时动力学详细研究碳转移途径，导致胸苷。总体而言，该项目正在定义许多酶现在被认为面对的催化策略和挑战。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的智力优点和更广泛影响的评估评估标准来通过评估来支持的。