Characterization of a glycoside hydrolase family 42 β-galactosidase from Deinococcus geothermalis.
A putative recombinant β-galactosidase from Deinococcus geothermalis was purified as a single 79 kDa band of 42 U activity/mg using His-Trap affinity chromatography. The molecular mass of the native enzyme was a 158 kDa dimer. The catalytic residues E151 and E325 of β-galactosidase from D. geothermalis were conserved in all aligned GH family 42 β-galactosidases, indicating that this enzyme is also a GH family 42 β-galactosidase. Maximal activity of the enzyme was at pH 6.5 and 60°C. It has a unique hydrolytic activity for p-nitrophenyl(pNP)-β-D-galactopyranoside (k (cat)/K (m) = 69 s(-1) mM(-1)), pNP-β-D-fucopyranoside (13), oNP-β-D-galactopyranoside (9.5), oNP-β-D-fucopyranoside (2.6), lactose (0.97), and pNP-α-L-arabinopyranoside (0.78), whereas no activity, or less than 2% of the pNP-β-D-galactopyranoside activity, for other pNP- and oNP-glycosides.
Department of Bioscience and Biotechnology, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul, 143-701, Republic of Korea.
Jae-Hee
JH
Lee
Yeong-Su
YS
Kim
Soo-Jin
SJ
Yeom
Deok-Kun
DK
Oh
D034301:Deinococcus / Q000201:enzymology*; D006026:Glycoside Hydrolases / Q000235:genetics / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D013379:Substrate Specificity; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism*
D006026:Glycoside Hydrolases; D001616:beta-Galactosidase