The enzymes used to carry out chemical or biological transformations are often difficult to separate from the reaction mixtures in which they are found. One-time use of an enzyme, however, is expensive. This has motivated a large body of research on enzyme immobilization. The goals of this project are to develop a simple method to permit repeated use of an enzyme along with enhanced enzyme stability and, if possible, activity. A new immobilized enzyme system is to be developed that will convert solid or macromolecular substrates, something that many other immobilized systems are not suited to do. This will be based on conjugating the enzyme (or enzyme complex) to a water-soluble polymer that is sensitive to temperature, or in some cases, to both temperature and pH. Temperature sensitive polymers exhibit a lower critical solution temperature (LCST) when dissolved in water. Such polymers precipitate from solution when the temperature is raised above the LCST. This occurs when the polymer is conjugated to a protein. At any time during or after the enzymatic reaction, the polymer-enzyme complex may be reversibly precipitated from the reaction solution, facilitating product recovery and recycle of the enzyme.
