Purification of New β-Galactosidase from Enterococcus faecium MTCC 5153 with Transgalactosylation Activity
2011
Badarinath, Vure | Halami, Prakash M.
A new beta-galactosidase (beta-gal) was purified from a lactic acid bacterial strain of Enterococcus faecium MTCC5153 by chromatographic techniques. The purified enzyme had a specific activity of 24.06 U/mg of protein with k m and Vmax values of 2 mM and 18.2 mM/min/mg of protein, respectively. The yield of purified β-gal was 10.65% and estimated molecular weight found to be 90 kDa, consisting of two homodimeric subunits of 43kDa. The enzyme was stable in pH range of 8.0-9.0 with an optimum pH of 8 and the optimum temperature of 40°C. The enzyme was activated in the presence of metal ions such as Mg+2, Mn+2, Ca+2, K+ and Na+ and was inhibited by Zn+2, Co+2 and Cu+2. Chemical modifiers (N-bromosuccinamide and Diethylpyro carbonate) inactivated the enzyme indicating the role of tryptophan and histidine moieties for activity. The purified β-gal was able to synthesize oligosaccharides from lactose. This study suggests that the beta-gal of Enterococcus faecium MTCC5153 could be applied in dairy industry for hydrolysis of lactose and to improve its digestibility. beta-gal of probiotic cultures are of particular interest due to their transgalactosylation properties.
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