Chris M. Olsen

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A bivalent recombinant vaccine for human hookworm disease is under development. One of the lead candidate antigens in the vaccine is a glutathione S-transferase cloned from the hookworm Necator americanus (Na-GST-1) which is expressed in the yeast Pichia pastoris. Based on preliminary studies demonstrating that the recombinant protein was not stable in an(More)
It has been shown that DNA oligonucleotides composed, in part, of G repeat sequences can adopt G-quadruplex structures in the presence of specific metal ions. In this work, we use a combination of spectroscopic and calorimetric techniques to determine the spectral and thermodynamic characteristics of two DNA aptamers, d(G2T2G2TGTG2T2G2), G2, and(More)
G-quadruplexes are a highly studied DNA motif with a potential role in a variety of cellular processes and more recently are considered novel targets for drug therapy in aging and anticancer research. In this work, we have investigated the thermodynamic contributions of the loops on the stable formation of G-quadruplexes. Specifically, we use a combination(More)
One focus of our research is to further our understanding of the physico-chemical properties of unusual DNA structures and their interaction with complementary oligonucleotides. We have investigated three types of reactions involving the interaction of intramolecular DNA complexes with their complementary single strands of varied length. Specifically, we(More)
A combination of spectroscopic and calorimetric techniques is used to investigate the unfolding of two G-quadruplexes: d(G2U2G2UGUG2U2G2), G2-U, and d(G2T2G2TGTG2T2G2), G2. The comparisons of their thermodynamic data allow us to elucidate the role of methylation on the energetic and hydration properties accompanying their stable formation. The favorable(More)
DNA oligonucleotides containing guanine repeat sequences can adopt G-quadruplex (GQ) structures in the presence of specific metal ions. We report on how to use a combination of spectroscopic and calorimetric techniques to determine the spectral characteristics and thermodynamic parameters for the temperature-unfolding of GQs. Specifically, we investigated(More)
The main focus of our investigations is to further our understanding of the physicochemical properties of nucleic acid structures. We report on a thermodynamic approach to study the reaction of a variety of intramolecular nucleic acid structures with their respective complementary strands. Specifically, we have used a combination of isothermal titration(More)
Topoisomerase 1 (Top1) enzymes regulate DNA superhelicity by forming covalent cleavage complexes that undergo controlled rotation. Substitution of nucleoside analogs at the +1 position of the DNA duplex relative to the Top1 cleavage site inhibits DNA religation. The reduced efficiency for Top1-mediated religation contributes to the anticancer activity of(More)
The fluorescence probe 2-aminopurine (2AP) is widely used to monitor the molecular environment, including the local solvent environment, and overall dynamics of nucleic acids and nucleic acid-ligand complexes. This work reports on the temperature-induced conformational flexibility of a variety of secondary structures of nucleic acids using optical and(More)
BACKGROUND The overall stability of DNA molecules globally depends on base-pair stacking, base-pairing, polyelectrolyte effect and hydration contributions. In order to understand how they carry out their biological roles, it is essential to have a complete physical description of how the folding of nucleic acids takes place, including their ion and water(More)
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