title: Characterization of the bga1-encoded glycoside hydrolase family 35 beta-galactosidase of Hypocrea jecorina with galacto-beta-D-galactanase activity.
abstract: The extracellular bga1-encoded beta-galactosidase of Hypocrea jecorina (Trichoderma reesei) was overexpressed under the pyruvat kinase (pki1) promoter region and purified to apparent homogeneity. The monomeric enzyme is a glycoprotein with a molecular mass of 118.8 +/- 0.5 kDa (MALDI-MS) and an isoelectric point of 6.6. Bga1 is active with several disaccharides, e.g. lactose, lactulose and galactobiose, as well as with aryl- and alkyl-beta-D-galactosides. Based on the catalytic efficiencies, lactitol and lactobionic acid are the poorest substrates and o-nitrophenyl-beta-D-galactoside and lactulose are the best. The pH optimum for the hydrolysis of galactosides is approximately 5.0, and the optimum temperature was found to be 60 degrees C. Bga1 is also capable of releasing D-galactose from beta-galactans and is thus actually a galacto-beta-D-galactanase. beta-Galactosidase is inhibited by its reaction product D-galactose and the enzyme also shows a significant transferase activity which results in the formation of galacto-oligosaccharides.
authors: Research Area Gene Technology and Applied Biochemistry, Institute of Chemical Engineering, Vienna University of Technology, Austria. gamauf@mail.zserv.tuwien.ac.at
authors: Christian
authors: C
authors: Gamauf
authors: Martina
authors: M
authors: Marchetti
authors: Jarno
authors: J
authors: Kallio
authors: Terhi
authors: T
authors: Puranen
authors: Jari
authors: J
authors: Vehmaanperä
authors: Günter
authors: G
authors: Allmaier
authors: Christian P
authors: CP
authors: Kubicek
authors: Bernhard
authors: B
authors: Seiboth
mesh_terms: D002384:Catalysis; D004187:Disaccharides / Q000737:chemistry / Q000378:metabolism; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D005685:Galactans / Q000737:chemistry / Q000378:metabolism; D005690:Galactose / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D006023:Glycoproteins / Q000737:chemistry / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000378:metabolism; D006031:Glycosylation; D006863:Hydrogen-Ion Concentration; D035901:Hypocrea / Q000737:chemistry / Q000201:enzymology*; D007700:Kinetics; D007785:Lactose / Q000737:chemistry / Q000378:metabolism; D007792:Lactulose / Q000737:chemistry / Q000378:metabolism; D008970:Molecular Weight; D009598:Nitrophenylgalactosides / Q000737:chemistry / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013379:Substrate Specificity; D013696:Temperature; D001616:beta-Galactosidase / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D004187:Disaccharides; D005656:Fungal Proteins; D005685:Galactans; D006023:Glycoproteins; C055012:2-nitrophenylgalactoside; D009598:Nitrophenylgalactosides; D007792:Lactulose; C056853:6-O-galactopyranosylgalactose; D006026:Glycoside Hydrolases; C089138:beta-galactanase; D001616:beta-Galactosidase; D007785:Lactose; C005653:arabinogalactan; D005690:Galactose