Characterization of galactooligosaccharides produced by β-galactosidase immobilized onto magnetized Dacron

摘要

Bioconversions using enzymes immobilized in magnetic supports present significant advantages due tothe easy separation of the enzyme from the reaction mixture and the simplicity and low cost of thesupport preparation. The characterization of the oligosaccharide mixture obtained by the action ofb-galactosidase covalently attached, via glutaraldehyde, to a hydrazideeDacronemagnetite composite ispresented. The fractionation of the oligosaccharide mixture by high performance liquid chromatography,followed by the analysis of the purified compounds by mass spectrometry and nuclear magnetic resonancespectroscopy permitted the identification of glucose, galactose, lactose and a hexose disaccharidecontaining a 1/6 linkage. Also, the following GOS were identified: b-D-Galp-(1/6)-b-D-Galp-(1/4)-Glcp, b-D-Galp-(1/4)-[b-D-Galp-(1/6)]-Glcp and b-D-Galp-(1/6)-b-D-Galp-(1/6)-b-D-Galp-(1/4)-Glcp. When GOS yield (26.2%) and kinetics of biotransformation of lactose by the Dacron immobilizedb-galactosidase were compared with values obtained for the enzyme immobilized in other magneticsupports, similar behaviour was observed