Ammonium ion requirement and stability of methanol dehydrogenase TTF-TCNQ electrodes

The ammonium ion requirement and stability of quinoprotein methanol dehydrogenases were investigated with a view to incorporating them in enzyme electrodes for alcohol. This involved consideration of the effect of temperature and polyelectrolytes on enzyme stability. A packed cavity electrode was constructed using the organic conducting salt TTF·TCNQ (tetrathiafulvalene–tetracyanoquinodimethane). Methanol dehydrogenase isolated from Paracoccus denitrificans was more stable than the enzyme isolated from Methylophilus methylotrophus and was successfully used for repeated assay in packed cavity electrodes without significant loss in current output. These investigations also showed that, contrary to suggestions in the literature, ammonium ions are necessary for efficient re-oxidation of methanol dehydrogenase at the organic conducting salt electrode.