I'm thrilled to share my co-first-author paper with Advait Hasabnis in the Journal of the American Chemical Society where we introduce the notion of amplifying chemical shift sensitivity of fluorine #NMR protein tags by linking the #19F reporter to a dynamic tautomeric species!
We were puzzled as to why the current paradigm in NMR tag design still relies solely on the intrinsic sensitivity of the nucleus while fluorescent probes for optical spectroscopy have undergone extensive rational design to modulate their photophysical properties and limit undesired energy transfer mechanisms.
We envisaged it might be possible to amplify the chemical shift response to changes in protein conformation by embedding the 19F reporter within 2-pyridone, a tautomeric molecule which *itself* changes between lactam to lactim states in response to the polarity of its environment.
We identified fluorinated pyridone tautomers that exhibited up to three-fold improvements in chemical shift sensitivity relative to our previous best-in-class protein NMR tag. In protein NMR applications, we found that labeling the alpha subunit of the stimulatory G protein as well as human serum albumin enabled us to delineate more functional states in the proteins' conformational ensembles that were unresolved by BTFMA!
At its core, our paper is a manifesto on the concept of a molecular "amplifier" in the design of NMR tags. We believe that there are alternative tautomer-based chemical shift amplifiers that could be used for 19F NMR. The ideal tautomer must 1) have well-defined chemical shift signatures for each tautomeric state, and 2) should undergo fast tautomerism. In addition to prototropic tautomers such as 2-pyridone, valence tautomerization is another opportunity that could be explored. For example, benzene oxide and oxepin undergo rapid valence tautomerism where the benzene oxide component is favored in polar solvents.
This was a long road filled with major challenges and hypothesis changes, and I'm so grateful for my talented colleagues in the Scott Prosser lab in organic chemistry, molecular biology, NMR spectroscopy, and computational chemistry as well as support from my co-supervisor Patrick Gunning and our collaborators Oleksandr Voznyy and Ernani Basso. This work would bever have been possible without their effort!
https://lnkd.in/gbTCsTZz
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1moThat’s awesome!