@article{Baltin_Akishev_Abeldenov_Silayev_Khassenov_2017, title={BIOCHEMICAL PROPERTIES OF RECOMBINANT Β-GALACTOSIDASE FROM STREPTOCOCCUS THERMOPHILUS}, url={https://biotechlink.org/index.php/journal/article/view/147}, abstractNote={<p>Recombinant β-galactosidase from <em>Streptococcus thermophilus</em> was successfully expressed in <em>Escherichia coli</em>, purified, and biochemically characterized. The gene encoding β-galactosidase was amplified from the genomic DNA of <em>St. thermophilus</em> and cloned into the expression vector pET-28c (+). Using the recombinant vector, a BL21 (DE3)/pLacZST strain-producer was obtained with overexpression of the gene. Optimal culture parameters for producing recombinant β-galactosidase were determined. The recombinant β-galactosidase had an activity of 19 units/mg. Biochemical characterization of recombinant β-galactosidase showed that the enzyme had maximum activity at pH 9.0 and temperature of 60°C. Analysis of the kinetics of lactose hydrolysis gave a Michaelis constant <em>K</em><sub>m</sub>of 10.12 ± 2.5 mM and a limiting value of the initial rate of the enzymatic reaction V<sub>max</sub>of 0.47 ± 0.027 mM/min. The β-galactosidase has been used in experiments that simulate commercial production conditions, to producea glucose-galactose syrup.</p>}, number={2}, journal={Eurasian Journal of Applied Biotechnology}, author={Baltin , K.K. and Akishev , Zh.D. and Abeldenov , S.K. and Silayev , D.V. and Khassenov , B.B.}, year={2017}, month={Jun.} }