Purification and properties of glucosyltransferase fromAureobasidium

Summary Purification and properties of glucosyltransferase, which produces panose (Glc16Glc14Glc) and isomaltose (Glc16Glc) from maltose (Glc14Glc), are reported. The enzyme, fromAureobasidium, was purified to homogeneity by fractionations involving ammonium sulfate and DEAE-Cellulofine, S-Sepharose Fast Flow and Sephadex G-200 chromatography. Molecular mass of the enzyme was estimated to be 395 kDa by gel filtration. The enzyme was identified as a glycoprotein which contains 32% (w/w) carbohydrate. The optimum pH for the enzymatic reaction was 4.5–5.5 and the enzyme was stable over a pH range of 4–6. The optimum reaction temperature for the enzyme was 65°C and the enzyme retained more than 96% activity at 60°C after 15 min. The enzyme produced panose from maltose by means of a high efficiency (45.5%) glucosyl-transfer reaction. The enzyme was inhibited by metal ions, such as those of mercury, silver and aluminum, and also by organic inhibitors, especially nitrilotriacetic acid.