Flap endonuclease 1 (FEN1) catalyzes the removal of 5’-flap structures generated by strand-displacement synthesis during lagging-strand DNA synthesis and long-patch base excision repair. Homozygous knockout of FEN1 in mice is embryonically lethal, whereas haploinsufficiency or catalytic deficiency due to mutation leads to rapid tumor progression, thereby illustrating the importance of FEN1 to genome stability. Despite its critical role in DNA replication and repair, a detailed mechanistic understanding of how FEN1 enzymes achieve substrate specificity and scissile phosphate selectivity without sequence information is still poorly understood. Detailed kinetic studies from the laboratory of Dr. Jane Grasby suggest that a concerted enzyme-substrate conformational change is essential to create a cleavage-competent FEN1-substrate complex. Testing such a hypothesis requires an arsenal of molecular, chemical, kinetic, biophysical, and structural techniques. Although such studies are already underway in the Grasby laboratory, one powerful tool missing from the ‘Grasby arsenal’ that would greatly compliment her current work is NMR relaxation dispersion (RD) experiments, which can identify at the atomic level sites in and quantify the time scale of motion. Combining NMR-RD data with biophysical data routinely obtained in her lab would allow for direct correlations between observed rates of reaction and conformation exchange processes occurring in the protein and substrate as has been done for RNase A. Although the University of Sheffield has the instrumentation and protein NMR expertise of Dr. Jeremy Waltho, the presence of a researcher experienced in both NMR and enzymology would increase the chances for success of and greatly expedite the completion of the project. As a graduate student and postdoctoral fellow, the coordinator gained experience in protein-nucleic acid NMR and enzymology, respectively, and thus, is well suited to this task.