New Approaches to Catalyst Screening and Development

点击翻译按钮获取中文摘要

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.