Structure and mechanism of soluble quinoprotein glucose dehydrogenase.
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Oubrie A, Rozeboom HJ, Kalk KH, Olsthoorn AJ, Duine JA, Dijkstra BW
Structure and mechanism of soluble quinoprotein glucose dehydrogenase.
EMBO J. 1999 Oct 1;18(19):5187-94.
- PubMed ID
- 10508152 [ View in PubMed]
- Abstract
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.