Enzymatic characterization of a maltogenic amylase from Lactobacillus gasseri ATCC 33323 expressed in Escherichia coli

A gene corresponding to a maltogenic amylase (MAase) in Lactobacillus gasseri ATCC 33323 ( lgma) was cloned and expressed in Escherichia coli. The recombinant LGMA was efficiently purified 24.3-fold by one-step Ni-NTA affinity chromatography. The final yield and specific activity of the purified recombinant LGMA were 68% and 58.7 U/mg, respectively. The purified enzyme exhibited optimal activity for β-CD hydrolysis at 55 °C and pH 5. The relative hydrolytic activities of LGMA to β-CD, soluble starch or pullulan was 8:1:1.9. The activity of LGMA was strongly inhibited by most metal ions, especially Zn 2+, Fe 2+, Co 2+ and by EDTA. LGMA possessed some unusual properties distinguishable from typical MAases, such as being in a tetrameric form, having hydrolyzing activity towards the α-(1,6)-glycosidic linkage and being inhibited by acarbose.