Purification and properties of β-galactosidase from Chaetomium thermophilum -ATCC 28076

A beta-Galactosidase (EC 3.2.1.23) with transglycosylation activity from the thermophilic fungus Chaetomium thermophilum (ATCC 28076) was isolated and purified to homogeneity by a four step purification scheme, comprising ammonium sulfate saturation, Bio Gel P-6 desalting, anion-exchange chromatography on Mono Q and molecular-sieve chromatography on Superose 12 columns. The molecular mass and pI of the purified enzyme were determined to be 55 kDa by SDS-PAGE and 5.85 - 6.0, respectively. HPLC analyses of the products indicated that the beta-galactosidase catalyzed the transglycosylation reaction. An increasing in trisaccharide content compared to the disaccharide was observed after 2h of incubation. For period longer than 18h an increase in tetrasaccharide content was established.