Abstract: A putative glycosidase family 3 gene (Leum _0289) was amplified from Leuconostoc mesentcroides ATCC 8293 genomic DNA and sub-cloned into the vector pET28a(+) to obtain a recombinant plasmid pET28a-Glu. The gene is composed of 2 226 bp nucleotides which encodes 742 amino acid residues with calculated molecular mass of 75 kDa. The enzyme assay results showed that the protein can not hydrolyze maltose, sucrose, cellobiose, lactose and gentiobiose except p-nitrohenyl-α-glucopyranoside substrate. The protein was then designated α-glucosidase. The optimum temperature and pH was 40℃ and 6.5, respectively. The enzyme is activated by Fe2+, Ca2+, Mg2+, but inhibited by Cu2+ and Zn2+.

Key words: Leuconostoc mesentcroides, gene cloning and expression, α-glucosidase