TABLE OF CONTENTS

This thesis describes protein structural changes in alkylammonium formate (AAF) ionic liquids. These proteins are dissolved in methylammonium formate (MAF), ethylammonium formate (EAF), and choline formate ionic liquids for study by fluorescence, circular dichroism, and UV-Visible spectroscopy. At room temperature, AAF solutions can maintain the native structure of proteins, such as cytochrome c and lysozyme, in relatively high ionic liquid concentrations (50%-70 % AAF/water or AAF/phosphate buffer pH 7.0) compared to similar solutions of the organic solvents, methanol or acetonitrile, with water or buffer. As temperature increases to 80 °C, AAF denatures proteins less than organic solvents. About 1/3 of the enzyme activity of cytochrome c in 80 % AAF/water can be maintained as compared to phosphate buffer. This fundamental biophysical information shows that AAFs have potential application as organic or salt solvent replacements for the separation of proteins in their native form by reversed phase or hydrophobic interaction liquid chromatography