Development of nanoelectrospray and application to protein research and drug discovery
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Mass spectrometry has become an indispensable tool to the biological analysis. It is widely used in protein research and pharmaceutical industries across many scientific disciplines. Electrospray and matrix-assisted laser desorption ionization are the two softest ionization methods used to transfer large biological molecules into the gas-phase as the intact charged ions. Nanoelectrospray, a miniaturized electrospray with improved ion transfer efficiency, is well-suited for the analysis of small volume biological samples. Polyaniline-coated nanoelectrospray emitters, developed in Wood's lab, have long life-lasting and are utilized in the nanoelectrospray source coupled with commercial QgTof to complete a series of top-down analysis. This approach is proved to be successful in protein drug target characterization, antibody sequencing and biomarker identification. 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. The multiple charge state distribution of the proteins can be reduced by the redox reagents such as 1,4-benzoquione or quinhydrone. The circular dichroism data demonstrated that the confirmation of the protein was not changed by admixing with the redox reagents and the high resolution FTMS data demonstrated that the proton transfer occurred during the charge state reduction. In general, this dissertation illustrates mass spectrometry is a valuable technique to solve a various structural problems of biological samples.