Immobilization and properties of Leuconostoc mesenteroids dextransucrase

Dextransucrase from Leuconostoc mesenteroides (NRRL B‐512F) was purified by ultrafiltration and gel filtration chromatography in 54% yield. The specific activity of a heart cut was 58.6 U/mg; cumulative purification of that preparation was 247−fold. Of 13 carriers surveyed, only alkylamine porous silica gave immobilization efficiencies consistently above 15 %. Immobilization to silica changed the properties of dextransucrase relatively little, the optimum pH for activity remaining at 5.2, while that for stability decreased from pH 5.5−6 to pH 5.2. In short assays, highest activities of both soluble and immobilized dextransucrase occurred at 30°C. Activation energies below that temperature were 8.6 kcal/mol for the former form and 1.7 kcal/mol for the latter. Maximum stabilization of soluble dextransucrase was attained by 5mM Ca2+.