Purification and properties of a heat-stable inulin fructotransferase from Arthrobacter ureafaciens

An inulin fructotransferase producing difructose dianhydride I (EC 2.4.1.200) was purified from Arthrobacter ureafaciens A51-1. It had maximum activity at pH 5.5 and 45degreesC, and was stable up to 80degreesC. This is the highest thermal stability for this enzyme reported to date. The molecular mass was estimated to be 38 000 by SDS-PAGE, and 61 000 by gel filtration. It was therefore estimated to be a dimer.