New Approaches to Catalyst Screening and Development

内布拉斯加大学林肯分校的研究小组利用化学催化、化学合成和生命过程化学项目的资助，正在开发新的反应，以帮助工业和制药部门以及学术界的化学家。该项目建立在一种称为原位酶筛选（ISES）的研究方法的基础上，利用酶作为催化报告者，促进反应发现和催化剂优化。该方法可帮助实验人员实时进行平行催化剂筛选，并促进反应发现。平行筛选方法对学术化学家和工业化学家都非常感兴趣，无论是在大型工业化学公司，还是在制药和生物技术公司的工艺方面。除了技术方面，该项目还将通过在包括化学合成、分析化学和化学生物学在内的跨学科研究环境中培训多样化的学生群体，帮助建立未来的STEM（科学、技术、工程和数学）劳动力。本提案的三个目标的目标平台反应建立在研究小组在开发含有“氟乙烯基触发器”的非天然氨基酸（AAs）方面建立的坚实基础之上。这项研究遵循了该小组早期的概念验证研究，表明α -（2 ' z -氟）乙烯基触发器和α -（1 ' -氟）乙烯基触发器对于PLP酶的基于机制的失活（MBI）具有很大的希望。每一类新的非天然氨基酸（AAs）都将在合成、药物和肽化学领域具有价值。本提案中的三个目标各有一个(i)合成/催化目标；（ii）筛选目标和（iii）化学生物学目标。本项目目的1是通过tm介导的分子内胺化反应对映选择性合成母体化合物L-和D- α -（1′-氟）乙烯基甘氨酸。初步研究表明“磷酸盐- ises”在一种新的荧光模式下。Ni（双膦）催化剂的研究取得了令人满意的结果，提供了一种高对映选择性的过渡金属催化剂。化学生物学研究将探索L-和D- α -（1 ' -氟）乙烯基甘氨酸抑制色氨酸合成酶的对映体选择性，以及与其他高价值酶一起检查这些对映体MBI候选物。目标2涉及乙烯基触发器（目标2A）和α -（1 ' -氟）乙烯基触发器（目标2B）的季铵化。实验工作指出，利用MNBDH染料指示剂，在这里使用碳酸盐离去基和醇氧化酶/过氧化物酶对的互补型荧光ISES的可能性。此外，初步筛选结果表明，在Pd（SiPhox）催化下，可以在高ee下获得季a-乙烯基AAs。Aim 3A和3B分别提出将催化化学发展为“侧链嵌入”的“1”-氟乙烯基”和“2”-氟乙烯基AAs。在化学生物学方面，一个令人兴奋的初步结果表明，“嵌入”1 ' -氟乙烯基是谷氨酸脱羧酶失活的触发因素。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With funding from the Chemical Catalysis, Chemical Synthesis, and Chemistry of Life Processes programs of the Division of Chemistry, the research team at the University of Nebraska-Lincoln is developing new reactions to help chemists in the industrial and pharmaceutical sectors and in academia. The project builds on a research approach termed In Situ Enzymatic Screening (ISES) to exploit enzymes as catalytic reporters to facilitate reaction discovery and catalyst optimization. The approach assists experimentalists in real time, enables parallel catalyst screening, and facilitates reaction discovery. Parallel screening methods are of great interest to both academic chemists and chemists in industry, in both the large industrial chemical companies and particularly on the process side in pharmaceutical and biotech companies. Beyond the technical aspects, the project will help to build the future STEM (science, technology, engineering, and mathematics) workforce by training a diverse group of students in an interdisciplinary research environment that includes elements of chemical synthesis, analytical chemistry, and chemical biology.The targeted platform reactions for each of the three aims of this proposal build on the strong foundation established by the investigator's group in developing unnatural amino acids (AAs) bearing “fluorovinyl triggers.” This research follows earlier proof of concept studies from the group, demonstrating that both the alpha-(2’Z-fluoro)vinyl trigger and the alpha-(1’-fluoro)vinyl trigger have great promise for the mechanism-based inactivation (MBI) of PLP enzymes. Each of the classes of novel unnatural amino acids (AAs) will be of value to the synthetic, medicinal and peptide chemistry communities, as well. The three aims in this proposal each have a (i) synthetic/catalytic goal; (ii) a screening goal and (iii) a chemical biology goal. Aim 1 of this project targets the enantioselective synthesis of the parent compound, L- and D- alpha-(1’-fluoro)vinylglycine via TM-mediated intramolecular amination. Preliminary studies demonstrate ‘phosphate-ISES’ in a new fluorescence mode. Promising results with Ni(bis-phosphine) catalysts are presented, offering a highly enantioselective route with an earth abundant transition metal catalyst. Chemical biology studies will probe the enantioselectivity of the inhibition of tryptophan synthase with L- and D- alpha-(1’-fluoro)vinylglycine, as well as examining these enantiomeric MBI candidates with other high value enzymes. Aim 2 involves the quaternization of both the vinyl trigger (Aim 2A) and of the alpha-(1’-fluoro)vinyl trigger (Aim 2B). Experimental work points to the possibility of using a complementary variant of fluorescence ISES here with carbonate leaving groups and alcohol oxidase/peroxidase couple using the MNBDH dye indicator. Moreover, preliminary screening results suggest that quaternary a-vinyl AAs can be accessed in high ee under Pd(SiPhox)-catalysis. Aim 3A and 3B propose to develop catalytic chemistry into new classes of ‘side chain-embedded’ 1’-fluorovinyl and 2’-fluorovinyl AAs, respectively. On the chemical biology side, an exciting preliminary result shows that the ‘embedded’ 1’-fluorovinyl is a trigger for glutamate decarboxylase inactivation.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.