New biocatalysts: myoglobin in phosphonium ionic liquids

New biocatalysts based on myoglobin in phosphonium ionic liquids were developed. This involved four general areas of research: (1) preparation of biocompatible phosphonium ionic liquids; (2) characterisation of myoglobin incorporated into ionic liquids; (3) biocatalysis involving myoglobin in phosphonium ionic liquids; and (4) prevention of protein denaturation by covalent modification of the protein. Three synthetic routes for preparation of new, biocompatible ionic liquids were investigated: sodium-salt metathesis, silver-salt metathesis, and acid-base neutralisation. Silver-salt metathesis was determined to be the most effective method for complete anion exchange. Spectroscopic analyses of myoglobin in ionic liquids demonstrated varying levels of denaturation depending on the concentration of ionic liquid. Nevertheless, myoglobin was shown to exhibit peroxidase-like activity in aqueous ionic liquid solutions. Unusual activity was observed for dibenzothiophene oxidation mediated by myoglobin in one ionic liquid. Covalent modification of myoglobin by poly(ethylene oxide) demonstrated improved stability of the protein in ionic liquids.