Abstract
Dye-linked dehydrogenases catalyze the electron transfer from amino acids, amines and alcohols to artificial electron acceptors such as 2,6-dichloroindophenol and ferricyanide. Their structural and functional information, and applications have been so far limited because of their low stability. We have carried out screening of the enzymes in hyperthermophiles and found three kinds of novel dye-linked proline dehydrogenases in hyperthermophilic archaea; tetrameric dye-linked L-proline dehydrogenase (αβγδ-type) from Thermococcus profundus, the octameric L-proline dehydrogenase (α_4β_4-type) from Pyrococcus horikoshii and tetrameric D-proline dehydrogenase from Pyrobaculum islandicum. We succeeded in biochemical characterization of the three enzymes and the 3D-structural analysis of the octameric enzyme, suggesting the presence of a novel electron transfer system in this hyperthermophile. In addition, we have constructed an electrochemical biosensor for L-proline determination using the stable dye-linked L-proline dehydrogenase as the application of dye-linked dehydrogenase.
