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Using recombinant DHFR protein as a model to study protein engineering

Dihydrofolate reductase (DHFR) is an enzyme that is essential in the generation of amino acids. For DHFR to properly carry out its functions, it requires a cofactor, NADPH. Looking at different chemical vendors, the cost of NADPH is around $530/gram. In a lab environment, carrying out this reaction multiple times would become cost prohibitive. Fortunately, a different cofactor, NADH, has a similar structure and is significantly cheaper. This means that if we could change DHFR to use NADH instead of NADPH, we could cut lab costs for this experiment. Here, we take preliminary steps to generate mutant DHFR by changing two amino acids from the native enzyme, Serine-76 and Lysine-54, that were identified to interact with the phosphate group and replacing them with Isoleucine-76 and Glutamate-54, respectively, via mutagenesis. We used E. coli as our host organism and performed mutagenesis to generate the mutant plasmids. To date, a functional mutant has not yet been produced. When a mutant is successfully produced, classic enzymology (a functional assay) will be done to determine whether or not the mutant can bind preferentially to NADH.

Shealynn Conway '22, Michael O'Shaughnessy '22,  Anna Postnikova '22
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