Causes of the Production of Multiple Forms of [beta]-Galactosidase by Bacillus circulans

• Published in: Bioscience, biotechnology, and biochemistry Vol. 75; no. 2; p. 268
• Main Authors: SONG, Jingyuan, ABE, Kiriko, IMANAKA, Hiroyuki, IMAMURA, Koreyoshi, MINODA, Masashi, YAMAGUCHI, Shotaro, NAKANISHI, Kazuhiro
• Format: Journal Article
• Language: English
• Published: Tokyo Oxford University Press 01.02.2011
• ISSN: 0916-8451; 1347-6947

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.