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Date of Award

3-26-2019

Document Type

Thesis and Dissertation-ISU Access Only

Degree Name

Master of Science (MS)

Department

Department of Chemistry

First Advisor

Jon Friesen

Abstract

Choline kinase catalyzes the conversion of choline to phosphocholine by transferring a phosphate group from adenosine triphosphate (ATP) as the first step in the biosynthetic pathway for the membrane phospholipid phosphatidylcholine, an essential pathway in the Leishmania parasitic protozoan. Commonly used methods for kinetically quantifying the enzyme include a radioisotope assay utilizing labeled choline and a coupled spectrophotometric assay with multiple enzymes and substrates that indirectly measures choline kinase activity. When testing potential inhibitors with the coupled assay, results can cast doubt on whether choline kinase is being inhibited or one of the coupled enzymes. Therefore, 31P NMR spectroscopy was used to quantitatively measure the formation of the key product, phosphocholine, and to evaluate choline kinase activity. Interrogation of 31P NMR spectroscopy offers a number of benefits. Since this isotope is 100% abundant and has a relatively large gyromagnetic ratio, it is considered one of the more sensitive nuclides. As such, the need for costly isotopic enriched phosphorous is not required and detection of the 31P signal is possible even at relatively low concentrations. The enzymatic activity of Leishmania infantum choline kinase was able to be directly measured via integration of the 31P resonance associated with the phosphocholine product (δ= 3.94 ppm). These initial studies reveal that a 31P NMR spectroscopic-based assay could be used for testing substrate or transition state analogs as competitive inhibitors of Leishmania choline kinase that may prevent phosphatidylcholine synthesis in the parasite.

Comments

Imported from ProQuest Walker_ilstu_0092N_11426.pdf

DOI

http://doi.org/10.30707/ETD2019.Walker.J

Page Count

54

Available for download on Friday, June 11, 2021

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