Oxidizes glucose to gluconolactone. a ubiquinone + D-glucose = a ubiquinol + D-glucono-1,5-lactone Binds 1 PQQ group per subunit. Binds 3 Ca(2+) ions per subunit. Homodimer. Potent biocatalyst for the accurate in vivo monitoring of blood glucose in the management of diabetes. Acinetobacter calcoaceticus contains two different PQQ dependent enzymes with GDH activity. GDH-A prefers 2-deoxyglucose as substrate, the specific substrates for GDH-B are disaccharides. Belongs to the PQQ oxidoreductase GdhB family.