Isobaric Labeling Proteomics Allows a High-Throughput Investigation of Protein Corona Orientation

The
formation of the biomolecular corona represents a crucial factor
in controlling the biological interactions and trafficking of nanomaterials.
In this context, the availability of key epitopes exposed on the surface
of the corona, and able to engage the biological machinery, is important
to define the biological fate of the material. While the full biomolecular
corona composition can be investigated by conventional bottom-up proteomics,
the assessment of the spatial orientation of proteins in the corona
in a high-throughput fashion is still challenging. In this work, we
show that labeling corona proteins with isobaric tags in their native
conditions and analyzing the MS/MS spectra of tryptic peptides allow
an easy and high-throughput assessment of the inner/outer orientation
of the corresponding proteins in the original corona. We put our results
in the context of what is currently known of the protein corona of
graphene-based nanomaterials. Our conclusions are in line with previous
data and were confirmed by in silico calculations.