Purification and characterisation of an intracellular enzyme with beta-glucosidase and beta-galactosidase activity from the thermophilic fungus Talaromyces thermophilus CBS 236.58.
An intracellular beta-glycoside hydrolase with beta-glucosidase and beta-galactosidase activity, designated beta-glucosidase BGL1, was isolated to apparent homogeneity from the thermophilic ascomycete Talaromyces thermophilus CBS 236.58. The monomeric enzyme has a molecular mass of 50 kDa (SDS-PAGE) and an isoelectric point of 4.5-4.6. The enzyme is active with both glucosides such as cellobiose and galactosides including lactose; based on the catalytic efficiencies determined glucosides are the preferred substrates. beta-Galactosidase activity of BGL1 is activated by various mono and divalent cations including Na+, K+ and Mg2+, and it is moderately inhibited by its reaction products glucose and galactose. Its pH optimum for the hydrolysis of galactosides is in the range of 5.5-6.0, and its optimum temperature was found to be 50 degrees C (15 min assay). In addition to its hydrolytic activity, BGL1 shows a significant transferase activity which results in the formation of galacto-oligosaccharides. These have recently attracted interest because of possible applications in food industry. The highest yields of oligosaccharides was approximately 20% when using 38 gl(-1) lactose as the starting material.
Nakkharat
Phimchanok
P
Division of Food Biotechnology, Department of Food Science and Technology, BOKU, University of Natural Resources and Applied Life Sciences, Vienna Muthgasse 18, A-1190 Vienna, Austria.
Haltrich
Dietmar
D
D044602:Cellulases / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D004789:Enzyme Activation; D004795:Enzyme Stability; D007424:Intracellular Fluid / Q000378:metabolism; D007527:Isoenzymes / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D008970:Molecular Weight; D009844:Oligosaccharides / Q000737:chemistry*; D013379:Substrate Specificity; D032901:Talaromyces / Q000201:enzymology*; D001616:beta-Galactosidase / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism
D007527:Isoenzymes; D009844:Oligosaccharides; D044602:Cellulases; D001616:beta-Galactosidase