Assessing stability of supercharged proteins in single levitated microdroplets

Viola Fieglein - Texas State University

12:15 - 12:30 Wednesday 10 June Morning

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Abstract

Biomolecule stability in aerosols has been widely studied in recent years due to their unique interactions at the air-water interface; however, we still lack a fundamental understanding of the molecular mechanisms that drive their behavior in microdroplets. It is well understood that proteins adsorb at the air-water interface, but the effect of the interface on their stability remains unclear. Supercharged proteins have become of interest due to their increased stability, which can change protein properties without changing protein function. Here, we describe our recent work examining the dynamics of a supercharged model protein, green fluorescent protein (GFP), in levitated microdroplets. Microdroplets are levitated within a quadrupole electrodynamic trap (QET), and the folded state of GFP is assessed in situ by monitoring changes in fluorescence intensity over time. Our results show a correlation between the net charge on a protein and its stability within levitated droplets. Furthermore, we observe that supercharged proteins are less stable in smaller droplets and in droplets with large ionic strengths. These results demonstrate that interactions with the large, exposed surface areas can impact biomolecule stability in microdroplets, even for species with weak surface affinities. By gaining an understanding of how proteins interact with the air-water interface, we can apply this knowledge to a variety of biomolecules. Ultimately, we can use this work to get a fundamental understanding of how biomolecules behave at the interface and tease out surface-mediated interactions from other driving forces.

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