title: Characterization of galactosidases from Aspergillus niger: purification of a novel alpha-galactosidase activity.
abstract: An enzyme with beta-galactosidase activity and three proteins exhibiting alpha-galactosidase activity were purified from a culture filtrate of Aspergillus niger grown on arabinoxylan. beta-galactosidase, optimally active at pH 4 and 60-65 degrees C, was active against p-nitrophenyl-beta-D-galactopyranoside, lactose, and pectic galactan. It was not able to release galactose from sugar beet pectin or lemon pectin. Its action on pectic galactan was increased by the presence of beta-galactanase. The three forms of alpha-galactosidase activity that showed different molecular masses and pIs were found to have the same mass after deglycosylation with N-glycanase F and to be the same protein based on their N-terminal amino acid sequence data. The purified alpha-galactosidase was shown to be different from alpha-galactosidase A from A. niger. This confirmed the existence of at least two different alpha-galactosidases in A. niger. alpha-Galactosidase, optimally active at pH 4.5 and 50-55 degrees C, was active toward p-nitrophenyl-alpha-D-galactopyranoside, melibiose, raffinose, stachyose, and locust bean gum, on which substrate it exhibited synergism with beta-mannanase.
authors.affiliation: Section Molecular Genetics of Industrial Microorganisms, Wageningen Agricultural University, The Netherlands.
authors.forename: P
authors.initials: P
authors.lastname: Manzanares
authors.forename: L H
authors.initials: LH
authors.lastname: de Graaff
authors.forename: J
authors.initials: J
authors.lastname: Visser
mesh_terms: D000595:Amino Acid Sequence; D001234:Aspergillus niger / Q000201:enzymology* / Q000235:genetics; D004795:Enzyme Stability; D006031:Glycosylation; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D013379:Substrate Specificity; D013696:Temperature; D000519:alpha-Galactosidase / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D000519:alpha-Galactosidase