Structure and mechanism of soluble quinoprotein glucose dehydrogenase.
Soluble glucose dehydrogenase (s-GDH; EC 1.1.99.17) is a classical quinoprotein which requires the cofactor pyrroloquinoline quinone (PQQ) to oxidize glucose to gluconolactone. The reaction mechanism of PQQ-dependent enzymes has remained controversial due to the absence of comprehensive structural data. We have determined the X-ray structure of s-GDH with the cofactor at 2.2 A resolution, and of a complex with reduced PQQ and glucose at 1.9 A resolution. These structures reveal the active site of s-GDH, and show for the first time how a functionally bound substrate interacts with the cofactor in a PQQ-dependent enzyme. Twenty years after the discovery of PQQ, our results finally provide conclusive evidence for a reaction mechanism comprising general base-catalyzed hydride transfer, rather than the generally accepted covalent addition-elimination mechanism. Thus, PQQ-dependent enzymes use a mechanism similar to that of nicotinamide- and flavin-dependent oxidoreductases.
Oubrie
A
A
Laboratory of Biophysical Chemistry and BIOSON Research Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen.
Rozeboom
H J
HJ
Kalk
K H
KH
Olsthoorn
A J
AJ
Duine
J A
JA
Dijkstra
B W
BW
D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D018360:Crystallography, X-Ray; D005947:Glucose / Q000378:metabolism; D005948:Glucose Dehydrogenases / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012995:Solubility
D011994:Recombinant Proteins; D005948:Glucose Dehydrogenases; C033955:glucose dehydrogenase (pyrroloquinoline-quinone); D005947:Glucose; D002118:Calcium