A novel cold-active beta-D-galactosidase with transglycosylation activity from the Antarctic Arthrobacter sp 32cB-Gene cloning, purification and characterization

作者：Pawlak Szukalska Anna; Wanarska Marta^*; Popinigis Arkadiusz Tomasz; Kur Jozef

来源：Process Biochemistry, 2014, 49(12): 2122-2133.

DOI：10.1016/j.procbio.2014.09.018

• beta-D-Galactosidase
• Cold-active enzyme
• Arthrobacter sp 32cB
• Lactose hydrolysis
• Transglycosylation

A gene encoding a novel beta-D-galactosidase from the psychrotolerant Antarctic bacterium Arthrobacter sp. 32cB was isolated, cloned and expressed in Escherichia coli. The active form of recombinant beta-D-galactosidase consists of two subunits with a combined molecular weight of approximately 257 kDa. The enzyme's maximum activity towards o-nitrophenyl-beta-D-galactopyranoside was determined as occurring at 28 degrees C and pH 8.0. However, it exhibited 42% of maximum activity at 10 degrees C and was capable of hydrolyzing both lactose and o-nitrophenyl-beta-D-galactopyranoside at that temperature, with K-m, values of 1.52 and 16.56 mM, and k(cat) values 30.55 and 31.84 s(-1), respectively. Two units of the enzyme hydrolyzed 90% of the lactose in 1 mL of milk at 10 degrees C in 24 h. The transglycosylation activity of Arthrobacter sp. 32cB beta-D-galactosidase was also examined. It synthesized galactooligosaccharides in a temperature range from 10 to 30 degrees C. Moreover, it catalyzed the synthesis of heterooligosaccharides such as lactulose, galactosyl-xylose and galactosyl-arabinose, alkyl glycosides, and glycosylated salicin from lactose and the appropriate acceptor at 30 degrees C. The properties of Arthrobacter sp. 32cB beta-D-galactosidase make it a candidate for use in the industrial removal of lactose from milk and a promising tool for the glycosylation of various acceptors, especially those which are thermosensitive.

• 出版日期2014-12