The catalytical properties of glycosylated pyranose dehydrogenase (gPDH) and deglycosylated PDH (dgPDH) from Agaricus meleagris recombinantly expressed in Pichia pastoris were studied. Both gPDH and dgPDH were "wired" to an osmium redox polymer on graphite electrodes mounted in a flow-injection system. The current from oxidation of glucose by immobilised gPDH and dgPDH was compared using flow injection amperometry and cyclic voltammetry. An increase in the current density was observed for dgPDH (190 mu A cm(-2)) compared with that for gPDH (90 mu A cm(-2)) due to the improved electron transfer between the active site and the electrode. Additionally, the ability of dgPDH for direct electron transfer (DET) was discovered, which is rather unique among FAD-containing enzymes. The ability to oxidise a variety of sugars at a rather low potential makes dgPDH attractive for construction of biofuel cells with high power output. (C) 2012 Elsevier B.V. All rights reserved.