PRODUCTION OF LEUCROSE BY DEXTRANSUCRASE

Dextransucrase can be used to synthesize the disaccharide leucrose fro m sucrose and fructose under appropriate reaction conditions. HPLC met hods to analyze the reaction solutions and an enzyme activity test wer e developed to determine reaction kinetics and by-products in detail, As a result, a separate acceptor binding site at the enzyme was postul ated to explain all aspects of dextransucrase catalyzed reactions. The unconventional immobilization method for dextransucrase by entrapment in calcium alginate beads showed good results concerning activity, ef ficiency and operational stability. The immobilization mechanism was i nvestigated and the reaction conditions for leucrose formation were op timized. A surprising aspect was the finding, that yields and selectiv ity were much improved by reactions in ice. Referring to technical app lication of leucrose formation, the productivity of a continuous proce ss proved to be optimal in a tubular reactor; it compares favorably wi th a discontinuous use of the immobilized enzyme.