Honors Theses
Date of Award
Spring 5-2-2021
Document Type
Undergraduate Thesis
Department
Chemistry and Biochemistry
First Advisor
Randy Wadkins
Second Advisor
Saumen Chakraborty
Third Advisor
Susan Pedigo
Relational Format
Dissertation/Thesis
Abstract
DNA typically forms Watson and Crick double helix structures in which adenine, thymine, guanine, and cytosine pair with their complimentary DNA base. However, DNA i-motif structures can form in cytosine rich DNA, typically under slightly acidic conditions (~pH 6). DNA i-motifs are four stranded secondary structures in which cytosine pairs with cytosine to form a quadruplex. The i-motifs are typically formed in acidic conditions because of the protonation in the C•C base pair between one of the three hydrogen bases. Recent studies have suggested i-motifs can also form under neutral conditions, which is more realistic for a cell. It is important to study i-motifs because of their suggested role in gene expression, drug targeting, and drug delivery. The i-motifs can be studied under different physiological conditions and with the addition of crowding agents. The DNA strand DUX4L22 was used to study the formation of i-motifs from a pH range of 5.4 to 7.9 in solutions containing polyethylene glycol (PEG). These conditions mimic those found within a cell. The formation of i-motif structures was observed using circular dichroism spectroscopy. It was found that without the addition of a crowding agent, i-motif formation occurred at only acidic conditions. With the addition of 5% PEG 300, i-motif formation occurred at pH 7.1. With the addition of 20% PEG 300, i-motif formation occurred at pH 7.5. Lastly, with the addition of 30% PEG 300, i- motif formation occurred at pH 7.9. Therefore, it was concluded that with the addition of crowding agents, DNA i-motif formation can occur in basic physiological conditions for DUX4L22.
Recommended Citation
Rutherford, Lindsey, "Chemical and Co-Solute Effects of Polyethylene Glycol on i-Motif Formation" (2021). Honors Theses. 1787.
https://egrove.olemiss.edu/hon_thesis/1787
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