Location: Healthy Processed Foods ResearchTitle: Cloning, expression and structural stability of a cold-adapted ß-Galactosidase from Rahnella sp.R3 Author
|Fan, Yuting - Jiangnan University|
|Hua, Xiao - Jiangnan University|
|Feng, Yinghui - Jiangnan University|
|Shen, Qiuyun - Jiangnan University|
|Dong, Juan - Jiangnan University|
|Zhao, Wei - Jiangnan University|
|Zhang, Wenbin - Jiangnan University|
|Jin, Zhengyu - Jiangnan University|
|Yang, Ruijin - Jiangnan University|
Submitted to: Protein Expression and Purification
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2015
Publication Date: 7/3/2015
Citation: Fan, Y., Hua, X., Zhang, Y., Feng, Y., Shen, Q., Dong, J., Zhao, W., Zhang, W., Jin, Z., Yang, R. 2015. Cloning, expression and structural stability of a cold-adapted ß-Galactosidase from Rahnella sp.R3. Protein Expression and Purification. 115:158-164.
Interpretive Summary: A large percentage of the world population is afflicted with lactose intolerance. This has a negative impact on the marketing and utilization of milk products. Beta-galactosidase can be used in the manufacturing of lactose-reduced milk and other dairy products. It can also increase the sweetness of milk products as it convert lactose to glucose and galactose. It is desired to have Beta-galactosidase active at temperatures suitable for milk storage and transportation. This study reports the cloning, expression, purification, and characterization of a cold-adapted beta-galactosidase from psychrophilic gram-negative bacterium Rahnella sp.R3.
Technical Abstract: A novel gene was isolated for the first time from a psychrophilic gram-negative bacterium Rahnella sp.R3. It encoded a cold-adapted ß-galactosidase (R-ß-Gal). Recombinant R-ß-Gal was expressed in Escherichia coli BL21 (DE3), purified, and characterized. R-ß-Gal belongs to the glycosyl hydrolase family 42. Circular dichroism spectrometry studies of the structural stability of R-ß-Gal with respect to temperature indicated that the secondary structures of the enzyme were stable to 45°C. In solution, it was a homo-trimer and was active at temperatures as low as 4° C. The presence of metal ions was not required for the enzyme’s activity, but Mg2+, Mn2+, and Ca2+ enhanced its activity while Fe3+, Zn2+ and Al3+ deactivated it. The purified enzyme displayed a Km of 6.45 mM for ONPG and 2.19 mM for lactose at 4°C, respectively. These were lower than the corresponding Kms reported for other cold-adapted ß-Gals.