title: Causes of the production of multiple forms of β-galactosidase by Bacillus circulans.
abstract: The presence of multiple types of β-galactosidases in a commercial enzyme preparation from Bacillus circulans ATCC 31382 and differences in their transgalactosylation activity were investigated. Four β-galactosidases, β-Gal-A, β-Gal-B, β-Gal-C, and β-Gal-D, which were immunologically homologous, were isolated and characterized. The N-terminal amino acid sequences of all of the enzymes were identical and biochemical characteristics were similar, except for galactooligosaccharide production. β-Gal-B, β-Gal-C, and β-Gal-D produced mainly tri- and tetra saccharides at maximum yields of 20-30 and 9-12%, while β-Gal-A produced trisaccharide with 7% with 5% lactose as substrate. The Lineweaver-Burk plots for all of the enzymes, except for β-Gal-A, showed biphasic behavior. β-Gal-A was truncated to yield multiple β-galactosidases by treatment with protease isolated from the culture broth of B. circulans. Treatment of β-Gal-A with trypsin yielded an active 91-kDa protein composed of 21-kDa and 70-kDa proteins with characteristics similar to those for β-Gal-D.
authors.affiliation: Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan.
authors.forename: Jingyuan
authors.initials: J
authors.lastname: Song
authors.forename: Kiriko
authors.initials: K
authors.lastname: Abe
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Imanaka
authors.forename: Koreyoshi
authors.initials: K
authors.lastname: Imamura
authors.forename: Masashi
authors.initials: M
authors.lastname: Minoda
authors.forename: Shotaro
authors.initials: S
authors.lastname: Yamaguchi
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Nakanishi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001407:Bacillus / Q000201:enzymology / Q000378:metabolism*; D002417:Cattle; D004795:Enzyme Stability; D005690:Galactose / Q000378:metabolism; D007527:Isoenzymes / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D007785:Lactose / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D017386:Sequence Homology, Amino Acid; D014357:Trypsin / Q000378:metabolism; D001616:beta-Galactosidase / Q000096:biosynthesis* / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D001616:beta-Galactosidase; D014357:Trypsin; D007785:Lactose; D005690:Galactose