Nanoelectrospray mass spectrometry for molecular non-covalent interactions and proteomics
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Mass spectrometry has become an indispensable tool in biological analysis. Electrospray ionization is an important tool in the study and characterization of non-covalent molecular complexes because it is a soft ionization technique that preserves non-covalent binding stoichiometries. Nanoelectrospray, a miniaturized electrospray with improved ion transfer efficiency, is well-suited for the study of molecular non-covalent interactions. Polyaniline and graphite coated nanoelectrospray emitters, have long lifetimes and are utilized in the nanoelectrospray source coupled with commercial MS for the non-covalent interactions analysis and proteomics. Solution and gas-phase hydrogen/deuterium (H/D) exchange are promising methods in elucidating the solution or gas phase formation of non-covalent complexes. The H/D exchange technique is commonly used to provide insights into the roles of various non-covalent interactions in stabilizing the appropriate three-dimensional (3-D) structural information of solution and gaseous ions, including information on protein. We elucidated the mechanism of disulfide-bond reaction, and the specific role of hydrogen bonds in the formation of the disulfide linkages. This system provides an ideal platform to investigate the evolution of proteins. Additionally, the dual-functional nanoemitters are fabricated by immobilizing the trypsin onto the inner wall of the fused silica capillaries which are utilized as the nanoemitters with polyaniline coating as well. The diluted protein samples can be fast digested on line and are analyzed by the mass spectrometer without desalting. In general, this dissertation demonstrated the development of nanoelectrospray mass spectrometry for molecular non-covalent interactions and proteomics.