Improvement of enzyme function for use in organic media

The use of enzymes in non-conventional media is an important application of these highly selective catalysts. Enzymatic catalysis provides a route to the high product purity and reduced byproduct formation important to industrial and pharmaceutical production through inherent enantio-, chemo-, and regioselectivity. Enzyme use in organic media is necessary to integration with process conditions; however, enzymes typically exhibit very low activity when placed in such a non-native environment. Methods to increase enzyme activity in organic solvents are important to the continued development of these important catalysts. The work in this thesis focuses on improving the function of enzymes through formulation methods for use in organic media.; The formulation of the enzyme catalyst is a useful method to regain the loss in activity. In this work, two methods of enzyme formulation are used: enzyme lyophilization in the presence of non-buffer salts and immobilization to silica supports. Simple salts are known to dramatically increase catalytic activity of enzymes when formulated as a matrix around the enzyme through lyophilization. Immobilization to insoluble supports is a common method of enzyme formulation in industrial work, and the physical interaction between enzyme and support is important to enzyme activity.; The apparent effect of salt activation is correlated to a physicochemical property of the salt, the Jones-Dole B coefficient, which measures the strength of water-salt ion interactions. Both penicillin amidase, used in the production of semi-synthetic antibiotics, and soybean peroxidase, an oxidoreductase, are activated for use in organic media as salt formulated enzymes. Soybean peroxidase activity and selectivity are dependant on both the organic solvent used as well as the salt matrix.; Silica particles which present surface chemistries of varying hydrophobicities are used as supports for the covalent immobilization of enzymes. The surface hydrophobicity is found to influence enzyme catalysis in both aqueous and non-aqueous media. Candida antarctica Lipase B is a commonly used enzyme in the production of high value triglycerides. This enzyme immobilized to a highly hydrophobic support exhibits the greatest activity in both hydrolytic and synthetic reactions.