Nanoparticle technology has been a growing field in biomedical research. This is in part due to potential applications in drug delivery, biosensing, diagnostics, and imaging. Understanding the interactions, structure, and dynamics of biomolecules on nanoparticles is highly desirable. Solution NMR can be used as a novel method of identifying characteristics of biomolecules when they interact with nanoparticles. Our previous work suggests that the GB3 protein forms a monolayer on gold nanoparticle (AuNP) surfaces and remains globular. We have employed hydrogen-deuterium exchange (HDX) to probe the tertiary structure of GB3 when adsorbed. Remarkably, highly-protected residues on the AuNP surface are also highly protected in solution, and there is a strong correlation between HDX rates under both conditions. The HDX rates of the AuNP surface-bound protein were notably lower than the free protein in solution. These results suggest that adsorption increases the stability of GB3, and that this protein retains its native structure on the AuNP surface. The orientation of GB3 was determined by carrying out two novel experiments; competitive binding and methyl labeling of lysine residues. Lysine residues in the β-sheet region of GB3 were resistant to methylation when bound to AuNPs, suggesting that these residues are buried at the NP-biocorona interface. This result is supported by competitive binding experiments, which demonstrate that mutagenesis of β-sheet lysines significantly disrupts binding. The results reported here demonstrate that proteins can retain a stable, well-defined structure and orientation when adsorbed to NP surfaces, and may be significant for the general study of biomolecular protein coronas.<br/>

Structure and orientation of a small protein on a gold nanoparticle surface

255th National Meeting (2018)

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