Enhanced expression of the gene for beta-glycosidase of Thermus caldophilus GK24 and synthesis of galacto-oligosaccharides by the enzyme.
The gene (bglT) encoding Tca beta-glycosidase (Thermus caldophilus GK24 beta-glycosidase) was overexpressed under the control of the trp promoter on a high-copy-number plasmid, pTRPES, in Escherichia coli W3110. The purified Tca beta-glycosidase enzyme was used in a galactosyl-transfer reaction to synthesize galacto-oligosaccharides from lactose. The optimum temperature and pH for the enzyme to synthesize galacto-oligosaccharides from 30% (w/v) lactose were 80 degrees C and 6.0, respectively. The major product of the reaction was a trisaccharide. The thermostable Tca beta-glycosidase produced galacto-oligosaccharides efficiently during the hydrolysis of lactose.
Department of Genetic Engineering, Sungkyunkwan University, 300 Chunchun-Dong, Jangan-Ku, Suwon 440-746, South Korea.
Jeong Jin
JJ
Choi
Eun-Joo
EJ
Oh
Yoon-Jin
YJ
Lee
Dong Sang
DS
Suh
Jae Heung
JH
Lee
Soo-Won
SW
Lee
Hyung-Tai
HT
Shin
Suk-Tae
ST
Kwon
D000818:Animals; D004789:Enzyme Activation; D005690:Galactose / Q000378:metabolism*; D005822:Genetic Vectors; D006863:Hydrogen-Ion Concentration; D009844:Oligosaccharides / Q000096:biosynthesis*; D010957:Plasmids / Q000235:genetics; D013696:Temperature; D013824:Thermus / Q000201:enzymology* / Q000235:genetics; D013997:Time Factors; D001617:beta-Glucosidase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*
D009844:Oligosaccharides; D001617:beta-Glucosidase; D005690:Galactose