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Biochemistry, Biophysics, and Structural Biology

University of Mississippi

DNA

Publication Year

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Effects Of Group Ii Metal Binding On The Stability Of Dna I-Motif Structures, Charlotte Powers May 2023

Effects Of Group Ii Metal Binding On The Stability Of Dna I-Motif Structures, Charlotte Powers

Honors Theses

B-form DNA can adopt alternative structures while in superhelical duress. Alternative DNA structures are favored when there is an asymmetric distribution on complementary DNA strands. Cytosine rich strands may utilize cytosine-cytosine base pairing to form a four-stranded structure known as the i-motif (iM). The stability of iMs is affected by several factors such as DNA sequence, temperature, pH, ionic strength of the solution, and crowded conditions. While the effects of temperature, pH, and crowding conditions on iM stability have been well documented, the effects of ion presence in a solution has been less studied. Hence, those studies are the basis …


The Effects Of Crowding Agents On The Pka Of Physiologically Stable I-Motif Dna, Courtney Turner May 2022

The Effects Of Crowding Agents On The Pka Of Physiologically Stable I-Motif Dna, Courtney Turner

Honors Theses

The overall goal of this thesis was to investigate the environmental conditions that induce i-Motif folding of the DNA strand DUX4L22, a cytosine-rich segment of DNA found in the human genome. Cellular conditions were simulated using sodium cacodylate buffer and multiple weights of polyethylene glycol as a crowding agent. The presence of i-motifs were confirmed by Circular Dichroism spectroscopy. I found that DUX4L22 does form i-motifs under these physiological simulations at both acidic and neutral pHs. DUX4L22 therefore shows potential for use in studies of a wide variety of biotechnological advances, such as regulatory switches in nanomachines or drug-delivery systems.


Effects Of Crowding Agents On I-Motif Dna, Hayden Brines May 2021

Effects Of Crowding Agents On I-Motif Dna, Hayden Brines

Honors Theses

Deoxyribonucleic acid (DNA) is a well-known double stranded, helical, biological molecule. In addition to its more commonly known structure, DNA can also form more complicated structures like G-quadruplexes and i-motifs (iM). The iMs are formed by cytosine rich DNA and are a four stranded structure that is typically looped around itself. The iM formation is typically pH-dependent and is favored in more acidic conditions; the pKa value is approximately 6.5. This pKa value allows for potential in vivo formation, since the cells have a pH of approximately 7.3. Due to this, iMs are thought to be powerful, innovative molecules for …


Chemical And Co-Solute Effects Of Polyethylene Glycol On I-Motif Formation, Lindsey Rutherford May 2021

Chemical And Co-Solute Effects Of Polyethylene Glycol On I-Motif Formation, Lindsey Rutherford

Honors Theses

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 …