Partial purification and characterization of alpha-glucosidase from Pseudomonas fluorescens W

The alpha-glucosidase (alpha-D-glucoside glucohydrolase, EC 3.2.1.20) of Pseudomonas fluorescens W was partially purified by (NH4)2SO4 fractionation, Sephadex G-200 and DEAE-cellulose column chromatography. The enzyme showed great specificity for maltose hydrolysis, with very little action against polymeric forms. Sucrose, isomaltose, alpha-methylglucoside, and maltobionic acid were not hydrolyzed. Turanose was a strong competitive inhibitor, and glucose a weaker one. Tris (2-amino-2-hydroxymethylpropan-1:3-diol) inhibited enzyme activity significantly only at alkaline pH. Mercuric, cupric, and silver cations strongly inhibited, and EDTA (ethylenediaminetetraacetate) weakly inhibited the enzyme. The isolated enzyme was rather unstable even at 4 degrees C, and was destroyed by freezing and lyophilization. Inositol and albumin had a slightly protective effect. Sulfhydryl-binding reagents strongly inhibited the enzyme.