Date of Award

2019

Document Type

Thesis

Degree Name

Bachelors

Department

Natural Sciences

First Advisor

Shipman, Steven

Area of Concentration

Chemistry

Abstract

In the past decade, advances in protein analysis techniques have opened up new avenues of study for proteins that previously proved extremely difficult or time consuming to analyze with traditional x-ray crystallography. From improvements to NMR spectroscopy that allows the analysis of small proteins to the creation of cryo-EM that uses electron microscopy techniques to image proteins, there are more techniques to analyze proteins then before. Electrospray ionization mass spectrometry (ESI-MS) is one of those techniques and allows for charged proteins to be introduced to the gas phase with minimal disruption to their native conformations, and their masses determined. While yielding less structural data than the aforementioned techniques, ESI-MS is able to determine oligomeric states relatively simply, and is able to analyze proteins that prove difficult even with other modern methods. However, ESI-MS is far from perfect, requiring clean protein samples with few to no ions, such as Na+ present in the solution with the analyte. The presence of these salts can result in their adduction onto the analyte protein, and artificially increasing the mass of the protein. Many techniques are used to reduce the presence of these ions in solution, but there is no effective way to completely remove them. However, by reducing of the size of the electrospray capillary that emits the proteins during the electrospray process, it appears that the spectra of standard proteins can be improved slightly. These smaller tips apertures seem to promote higher charge states, and in the case of alcohol dehydrogenase, improve the signal to noise ratio of the spectra compared to standard tips. These improvements do suggest the possibility that protein spectra with large amounts of salt adduction may be improved with smaller apertures, but due to the already clear spectra from the standard proteins it is difficult to quantify the usefulness of these tips without performing a similar experiment on proteins more prone to salt adduction.

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