Enzymes can be used as catalysts to make or modify products. Fructose syrup, a sweetener competitive with sucrose used in food, is produced by isomerization of glucose using an immobilized form of the enzyme glucose isomerase. This represents the largest commercial application of an immobilized enzyme. The PI plans to design and develop an improved immobilized form of glucose isomerase to produce pure fructose syrup that can be used directly in soft drinks. The criteria for measuring performance of an immobilized glucose isomerase is its productivity in terms of total amount of fructose produced per unit of enzyme, determined by the combined effects of stability and activity. Activity and stability are very dependent upon both pH and temperature. For continuous use in fixed bed reactors, catalytic stability is the primary factor in determining the practical productivity of immobilized enzymes. The PI plans to design carrageenan-based supports for immobilized enzymes which should increase productivity and yield. The hypothesis is that carrageenan gels entrap the enzyme such that multiple sites on the gel interact with multiple sites on the surface of the enzyme by means of ionic bonds. Under such conditions the multi-point attachment of enzymes to solid supports conditions the multi-point attachment of enzymes to solid supports makes the enzyme more rigid and thus less susceptible to unfolding. This phase I work will involve: (1) Measuring the effects of pH and temperature on the stability and activity of the enzyme. (2) Determining sensitivity of the enzyme to O2 inactivation and Ca++ inhibition. (3) Measuring fructose yield under optimum conditions for productivity. The staff and instrumentation are more than adequate and funding is recommended.
