Expression of Streptomyces coelicolor .ALPHA.-Galactosidase Gene in Escherichia coli and Characterization

Abstract

An a-galactosidase gene belonging to glycoside hydrolase family ,1 from Streptomyces coelicolor was cloned and expressed in E. coli. The purified enzyme showed a single protein band on SDS-PAGE with a molecular mass of 0. kDa. It was quite stable from pH /.* to +*.* after treatment at .*ῌ for 0* min, and was thermally stable up to /*ῌ. The enzyme acted on galacto-oligosaccharides, galactomanno-oligosaccharides and galactomannans as well as plant a-galactosidases. It consisted of an N-terminal catalytic domain (.** amino acid residues) and a C-terminal region (,0* amino acid residues). The catalytic domain of the enzyme was constructed by deleting the C-terminal region from the enzyme and was found to be stable from pH /./ to 2./ and up to .*ῌ. The catalytic domain showed the same specificity towards galactooligosaccharides, galactomanno-oligosaccharides and galactomannans as the enzyme containing the Cterminal region. These results indicated that the C-terminal region probably has an important role in stabilizing the enzyme.

Enhancement of α- and β-Galactosidase Activity in Lactobacillus reuteri by Different Metal Ions

“…The addition of Na + and K + in the media enhanced the activity of α-galactosidase produced by L. reuteri MF14C strain in our study. However, the addition of Na + and K + did not show significant effect on α-galactosidase activity in previous mentioned reports [27][28][29][30][31]. But the addition of Na + and K + did significantly enhance the activity of β-galactosidase produced from B. longum CCRC 15708 [19].…”

“…Similarly, Garro et al [28] showed that 10 mM of Mn 2+ did not lead to an increase in α-galactosidase activity in L. fermentum CRL 251. Fridjonsson et al [29], Kondoh et al [30], and Carrera-Silva et al [31] showed that 1 mM of Mn 2+ did not significantly affect α-galactosidase activity in Streptomyces coelicolor, Thermus brockianus ITI360, and L. fermentum CRL 722, respectively. The addition of Na + and K + in the media enhanced the activity of α-galactosidase produced by L. reuteri MF14C strain in our study.…”