Abstract.
A β-galactosidase isoenzyme, β-GalI, from Bifidobacterium infantis HL96, was expressed in Escherichia coli and purified to homogeneity. The molecular mass of the β-GalI subunit was estimated to be 115 kDa by SDS-PAGE. The enzyme appeared to be a tetramer, with a molecular weight of about 470 kDa by native PAGE. The optimum temperature and pH for o-nitrophenyl-β-D-galactopyranoside (ONPG) and lactose were 60°C, pH 7.5, and 50°C, pH 7.5, respectively. The enzyme was stable over a pH range of 5.0–8.5, and remained active for more than 80 min at pH 7.0, 50°C. The enzyme activity was significantly increased by reducing agents. Maximum activity required the presence of both Na+ and K+, at a concentration of 10 mM. The enzyme was strongly inhibited by p-chloromercuribenzoic acid, divalent metal cations, and Cr3+, and to a lesser extent by EDTA and urea. The hydrolytic activity using lactose as a substrate was significantly inhibited by galactose. The K m and V max values for ONPG and lactose were 2.6 mM, 262 U/mg, and 73.8 mM, 1.28 U/mg, respectively. β-GalI possesses strong transgalactosylation activity. The production rate of galactooligosaccharides from 20% lactose at 30 and 60°C was 120 mg/ml, and this rate increased to 190 mg/ml when 30% lactose was used.
Article PDF
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
Author information
Authors and Affiliations
Additional information
Electronic Publication
Rights and permissions
About this article
Cite this article
Hung, .MN., Lee, .B. Purification and characterization of a recombinant β-galactosidase with transgalactosylation activity from Bifidobacterium infantis HL96. Appl Microbiol Biotechnol 58, 439–445 (2002). https://doi.org/10.1007/s00253-001-0911-6
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/s00253-001-0911-6