Levansucrases

Levansucrases (EC 2.4.1.10, β-D-fructofuranosyltransferases) transfer a fructosyl group from sucrose to a growing 2,6-β-D-fructan (levan) chain — or to other acceptors — extending the chain by one fructose unit while releasing glucose. Produced by bacteria (Bacillus, Zymomonas, Leuconostoc), they are useful biocatalysts for producing fructooligosaccharides and levan-type prebiotic sweeteners for functional foods from cheap sucrose. Controlling the reaction (acceptor availability, enzyme source, conditions) lets manufacturers tune chain length and branching for specific sweetness, solubility and fibre properties; they also explain dextran-like ropiness in some spoiled foods.