Hydrolyzes maltose-6'-phosphate and trehalose-6'-phosphate. Is involved in the catabolism of alpha-glycosides accumulated via a phosphoenolpyruvate-dependent maltose phosphotransferase system (PEP-PTS). Is also able to significantly catalyze the hydrolysis of both 6-phospho-alpha- and 6-phospho-beta-glucosides containing activated leaving groups such as p-nitrophenol and does so with retention and inversion, respectively, of the substrate anomeric configuration. alpha-maltose 6'-phosphate + H2O = D-glucose + D-glucose 6-phosphate Binds 1 divalent metal cation per subunit. Manganese, iron, cobalt or nickel enhance activity. Binds 1 NAD(+) per subunit. Is only active with NAD(+), not NADH. Cellobiose-6'-phosphate and 6-phospho-beta-D-glucopyranoside are not substrates but competitive inhibitors of GlvA. Optimum pH is about 7.6-8.4. Stable from pH 4.0 to 10.0. Homotetramer. By maltose; repressed by glucose. Reaction proceeds via a redox-elimination-addition mechanism consistent with an E1cb-type mechanism. This includes redox steps involving NAD(+) and stabilization of intermediates by Mn(2+). Because it hydrolyzes 6-phospho-alpha-glucopyranosides without activated leaving groups (such as maltose-6'-phosphate) but not glycosidic linkage of naturally occurring phospho-beta-glucosides such as cellobiose-6'-phosphate nor methyl 6-phospho-beta-D-glucopyranoside, GlvA is certainly more appropriately classified as a 6-phospho-alpha-glucosidase than as a 6-phospho-beta-glucosidase. The ability to hydrolyze beta-glycosidic linkages is exceptional and applies only to activated 6-phospho-beta-D-glucopyranosides. Belongs to the glycosyl hydrolase 4 family.