The quinoprotein dehydrogenases for methanol and glucose.
This review summarises our current understanding of two of the main types of quinoprotein dehydrogenase in which pyrroloquinoline quinone (PQQ) is the only prosthetic group. These are the soluble methanol dehydrogenase and the membrane glucose dehydrogenase (mGDH). The membrane GDH has an additional N-terminal domain by which it is tightly anchored to the membrane, and a periplasmic domain whose structure has been modelled on the X-ray structure of the alpha-subunit of MDH which contains PQQ in the active site. This review discusses their structures and mechanisms, concentrating particularly on the pathways for electron transfer from the reduced PQQ, through the protein, to their electron acceptors. In MDH, this is the specific cytochrome c(L), the electron transfer pathway probably involving the unique disulphide ring in the active site. By contrast, mGDH contains a permanently bound ubiquinone, which acts as a single electron carrier, mediating electron transfer through the protein to the membrane ubiquinone.
Anthony
Christopher
C
School of Biological Sciences, University of Southampton, Southampton SO16 7PX, UK. C.Anthony@soton.ac.uk
D000429:Alcohol Oxidoreductases / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D004579:Electron Transport; D004789:Enzyme Activation; D005947:Glucose / Q000737:chemistry / Q000378:metabolism*; D005948:Glucose Dehydrogenases / Q000737:chemistry* / Q000378:metabolism; D000432:Methanol / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D013329:Structure-Activity Relationship
D000429:Alcohol Oxidoreductases; D005948:Glucose Dehydrogenases; C019641:alcohol dehydrogenase (acceptor); C033955:glucose dehydrogenase (pyrroloquinoline-quinone); D005947:Glucose; D000432:Methanol