Investigation of possible driving forces on counter-intuitive thermal collapse of intrinsically disordered proteins

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)

Zachary Cormier (Creator)

Institution

East Carolina University (ECU )

Web Site: http://www.ecu.edu/lib/

Abstract: "Intrinsically disordered proteins are an emerging class of proteins that contain no secondary or tertiary structure. Through bioinformatics studies it has been predicted that a third of the human proteome consists of proteins containing intrinsic disorder. It was originally thought that a well-defined three dimensional structure was a prerequisite for function. However, this new class of proteins has been found to perform a variety of functions which has helped to establish new ways of classifying protein function. Intrinsically disordered proteins can undergo disorder-to-order transitions under different environmental factors. Of particular interest is a ""turned out"" response to increasing temperature. These proteins undergo a thermal collapse which is counter-intuitive to the traditional notion of protein folding and denaturation which states that under increasing temperature a protein should go into a more extended conformation. The reason for this counter-intuitive thermal collapse is still unknown. The goal of our research was to find the main driving force behind thermal collapse of intrinsically disordered proteins. Utilizing circular dichroism, the structure and transitions of four polypeptides (prothymosin-alpha (50-89)N50W, scrambled prothymosin-alpha (50-89), scrambled prothymosin-alpha (50-89) in 1M KF, and a polyE peptide) where analyzed under increasing temperatures of 25 [degrees]C to 80 [degrees]C to observe the possible effects of net charge, hydrophobicity, and sequence specificity on the thermal collapse of intrinsically disordered proteins. All peptides collapsed to similar degrees under increasing temperatures. The ionic strength condition appeared to be more collapsed than the non-salt condition indicating net charge as a major player. The hydrophobic effect also appears to play a major role in counter-intuitive collapse which may be attributed to the change in hydrophobicity of polar side chains."

Additional Information

Publication

Thesis

Language: English

Date: 2016

Keywords

Counter-Intuitive Thermal Collapse, Intrinsically Disordered Proteins

Subjects

Proteins--Analysis; Polypeptides; Circular dichroism

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