Alpha-glycosidase with a very broad specificity. Hydrolyzes maltose and other small maltooligosaccharides but is inactive against the polymeric substrate starch. AglA is not specific with respect to the configuration at the C-4 position of its substrates because glycosidic derivatives of D-galactose are also hydrolyzed. Does not cleave beta-glycosidic bonds. Hydrolysis of terminal, non-reducing (1->4)-linked alpha-D-glucose residues with release of alpha-D-glucose. Binds 1 NAD(+) per subunit. Binds 1 Mn(2+) ion per subunit. Can also use Co(2+) and Ni(2+) ions, albeit less efficiently than manganese ion. Inhibited by Hg(2+) ion and EDTA. Optimum pH is 7.5. Active from pH 6.5 to 9. Optimum temperature is 90 degrees Celsius. Active from 60 to 105 degrees Celsius. Highly thermostable. Homodimer. Belongs to the glycosyl hydrolase 4 family. In the crystal structure (PubMed:12588867), the metal ion is absent, probably due to the oxidation of the active site Cys-174 to sulfinic acid. In the absence of metal, positions of the coenzyme and the substrate and their interactions are all significantly altered, presumably accounting for the inactivity of this form.