Date Thesis Awarded
Honors Thesis -- Open Access
Bachelors of Arts (BA)
John C. Poutsma
Mark H. Forsyth
Hydrogen-Deuterium Exchange Experiments: The first study presented in this thesis describes the hydrogen-deuterium exchange behavior of protonated lysine and its three shorter homologs ornithine, diaminobutyric acid (DABA), and diaminopropionic acid (DAPA). H/D exchange reactions were conducted in an ion trap mass spectrometer with an external electrospray ionization source. All four of the amino acids studied exhibited complete exchange of all six labile hydrogens, but at significantly different rates. DAPA exchanged at the fastest rates, followed by lysine, and then DABA. Ornithine was shown to exchange at substantially slower rates than the other three homologs. Computational modeling of the H/D exchange reactions were performed to help explain these experimental results. Energetic barriers for the proposed exchange mechanisms do not sufficiently account for the large difference in exchange rate coefficients between DAPA and ornithine. Additional modeling must be completed to fully explain this phenomenon. Construction of Nanospray Ionization Source and Proteomics Experiments: A nanospray ionization source was also constructed for interfacing the ion trap mass spectrometer with high performance liquid chromatography. This instrument was used to separate and analyze peptides from tryptic digestions. The superior sensitivity of nanospray was needed to detect small quantities of peptide from complex mixtures. This instrument will be used to study the protein expressions of the Cluster K bacteriophage. Tandem mass spectrometry, in conjunction with the sequencing software SEQUEST, will be used to identify bacterial and viral proteins from tryptic digest samples.
Straus, Rita N., "Hydrogen Deuterium Exchange of Lysine Homologs and Construction of a Nanospray Ionization Source" (2012). Undergraduate Honors Theses. William & Mary. Paper 477.
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