The purpose of this project was to develop tools for identifying the sequence of peptides/proteins by covalently labeling free amine groups of the peptide/protein with N-hydroxysuccinimidyl (NHS) ester modified Fe3O4@SiO2 nanoparticles (NPs) containing a non-disulfide ethylene glycol linker. The reaction can be performed at physiological pH at room temperature to preserve the native state of proteins. Fe3O4@SiO2 NPs were prepared and functionalized with a homobifunctioal cross linker containing NHS ester groups with a non-disulfide bond linker, which can be cleaved without breaking the disulfide bonds in the proteins. The nanoparticle-peptide conjugates were separated using a magnet and cleaved using hydroxylamine-HCl.  Resulting labeled peptides were analyzed by LC-MS/MS. From the mass spectra, two peaks were found to match the free amine groups from the original peptide sequence. Fragmentation patterns observed by MS/MS matched the precursor peptide. This approach allows breaking of disulfide bonds in proteins for efficient digestion without affecting the cleavable bond present on the surface of the NPs.  Benefits include specificity towards primary amine groups in peptide, low cost, and rapid and effective magnetic separation.

Cleavable ethylene glycol linked NHS ester modified Fe?3?O?4@SiO?2? nanoparticles for covalent labeling of primary amine groups of peptides

247th National Meeting (2014)

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