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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Healthy Processed Foods Research » Research » Publications at this Location » Publication #321024

Research Project: Defining, Measuring, and Mitigating Attributes that Adversely Impact the Quality and Marketability of Foods

Location: Healthy Processed Foods Research

Title: Cloning, expression and structural stability of a cold-adapted ß-Galactosidase from Rahnella sp.R3

item FAN, YUTING - Jiangnan University
item HUA, XIAO - Jiangnan University
item Zhang, Yuzhu
item FENG, YINGHUI - Jiangnan University
item SHEN, QIUYUN - Jiangnan University
item DONG, JUAN - Jiangnan University
item ZHAO, WEI - Jiangnan University
item ZHANG, WENBIN - Jiangnan University
item JIN, ZHENGYU - Jiangnan University
item 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.