Characterization of Polymers and Supramolecular Protein-polymer Bioconjugates Using Mass Spectrometry

Download or read book Characterization of Polymers and Supramolecular Protein-polymer Bioconjugates Using Mass Spectrometry written by Yuan Gao and published by . This book was released on 2021 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mass spectrometry (MS) is increasingly used for the characterization of polymers and supramolecular protein-polymer bioconjugates; especially after the introduction of soft ionization methods such as electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI). Regular MS measures molecular weight information by detecting the mass-to-charge (m/z) ratio. However, if analyzing the structure of a complicated molecule such as a protein-polymer bioconjugate, information besides the molecular mass is necessary. Tandem MS (MS/MS), which involves isolation and fragmentation of a precursor ion, is widely used to gain more detailed structural information. MALDI-MS is a powerful technique for the analysis of polymers. One of the most important steps for MALDI analysis is sample preparation. MALDI sample preparation aims of producing densely packed microcrystals that improve mass accuracy, resolution, and shot-to-shot reproducibility as compared to large crystals. This thesis compared three common sample preparation methods for MALDI analysis: Dried droplet, solvent-free MALDI (SF-MALDI), and surface-layer MALDI (SL-MALDI). Additionally, ESI-MS and ESI-MS/MS were used to characterize supramolecular protein-polymer bioconjugates. Acidic polymers such as poly(styrene sulfonate) (PSS) were used to form non-covalent complexes with ubiquitin, a protein with many basic amino acid binding sites. Based on studies with simple peptides, MS/MS fragmentation of the ubiquitin complexes should cause cleavages in the protein backbone but preserve the non-covalent interaction. This study will apply a method to determine the attachment site of the polymer, which would reveal the surface-accessible basic amino acid residues and the higher-order structure of ubiquitin.