Volume 50, Issue 4 pp. 164-172
Research Paper

Production of Leucrose by Dextransucrase

Klaus BuchholzMartina Noll-Borchers

Martina Noll-Borchers

Lehrstuhl für Technologie der Kohlenhydrate, Technische Universität, Virchowstr. 2, 45470 Mülheim (Germany)

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Dieter Schwengers

Dieter Schwengers

Lehrstuhl für Technologie der Kohlenhydrate, Technische Universität, Liesentorweg 12, 47802 Krefeld (Germany)

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Abstract

Dextransucrase can be used to synthesize the disaccharide leucrose from sucrose and fructose under appropriate reaction conditions. HPLC methods to analyze the reaction solutions and an enzyme activity test were developed to determine reaction kinetics and by-products in detail. As a result, a separate acceptor binding site at the enzyme was postulated 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, efficiency and operational stability. The immobilization mechanism was investigated and the reaction conditions for leucrose formation were optimized. A surprising aspect was the finding, that yields and selectivity were much improved by reactions in ice. Referring to technical application of leucrose formation, the productivity of a continuous process proved to be optimal in a tubular reactor; it compares favorably with a discontinuous use of the immobilized enzyme.

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