| 摘要 |
PURPOSE:To obtain the subject new enzyme having specific physicochemical properties, high in the transglucosylation ability to stevioside etc., capable of mass-producing a transglucosylation product as a raw material for various foods and medicines, by culturing Klebsiella bacteria. CONSTITUTION:Bacteria belonging to Klebsiella [e.g. Klebsiella oxytoca A-53 (FERM P-14263)] are cultured in a medium, and the resultant culture fluid is centrifuged to collect the bacteria, and these microbes are subjected to ultrasonic crushing in a buffer solution followed by centrifugal separation to take the resultant supernatant, which is, in turn, put to anion exchange chromatography followed by gel filtration to effect purification, thus obtaining the objective new beta-galactosidase which has the following characteristics: capable of hydrolyzing beta-D-galactoside linkage, and having activity to transfer the resultant D-galactose group; optimum pH: 7.0-7.5; stable at pH6.5-7.5 (after treatment at 40 deg.C for 60min); optimum temperature for activity: 30-40 deg.C; and molecular weight (determined by gel filtration method): 320000. |
