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The Haglund group focus on the folding and function of proteins with a complex topology, utilizing both computational and experimental techniques. In 2012, Dr. Haglund discovered a new class of “knot-like” motifs called Pierced Lasso Topologies (PLTs). Interestingly, these threaded topologies exist in all kingdoms of life, and populate 18% of known protein structures containing one disulfide bond. To understand the biological role of PLTs in human health, we study the folding and function of three strategically selected model systems: the pleiotropic hormone leptin, the CXC and CC chemokines, and the enzyme superoxide dismutase (SOD).

Pierced Lasso Topology (PLT)

Under oxidizing conditions, a protein can form a disulfide bridge between two cysteines that are in close proximity. If one of the residues is positioned in the middle of the sequence and the other at the terminal, a lasso-like structure is formed. When part of the polypeptide chain backbone threads through the covalent loop, this forms a pierced lasso (PL).

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Biophysical Characterization

Several techniques are utilized to analyze and biophysically characterize our model proteins including but not limited to: circular dichroism, stopped-flow, nuclear magnetic resonance (NMR), in cell biological assays, and in vivo model systems utilizing Drosophila melanogaster to molecular dynamics simulations.

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