Investigation of the mechanism of action of pyrogallol-phloroglucinol transhydroxylase by using putative intermediates.
Pyrogallol-phloroglucinol transhydroxylase from Pelobacter acidigallici, a molybdopterin-containing enzyme, catalyzes a key reaction in the anaerobic degradation of aromatic compounds. In vitro, the enzymatic reaction requires 1,2,3,5-tetrahydroxybenzene as a cocatalyst and the transhydroxylation occurs without exchange with hydroxy groups from water. To test our previous proposal that the transfer of the hydroxy group occurs via 2,4,6,3',4',5'-hexahydroxydiphenyl ether as an intermediate, we synthesized this compound and investigated its properties. We also describe the synthesis and characterization of 3,4,5,3',4',5'-hexahydroxydiphenyl ether. Both compounds could substitute for the cocatalyst in vitro. This indicates that the diphenyl ethers can intrude into the active site and initiate the catalytic cycle. Recently, the X-ray crystal structure of the transhydroxylase (TH) was published16 and it supports the proposed mechanism of hydroxy-group transfer.
Paizs
Csaba
C
Institute of Organic Chemistry and Biochemistry, University of Karlsruhe, Richard-Willstätter-Allee, 76128 Karlsruhe, Germany.
Bartlewski-Hof
Ulrike
U
Rétey
János
J
D000693:Anaerobiosis; D001665:Binding Sites; D002384:Catalysis; D003067:Coenzymes / Q000378:metabolism; D018360:Crystallography, X-Ray; D006900:Hydroxylation; D008667:Metalloproteins / Q000378:metabolism; D008956:Models, Chemical; D000090006:Molybdenum Cofactors; D010088:Oxidoreductases / Q000378:metabolism*; D010636:Phenols / Q000138:chemical synthesis*; D010647:Phenyl Ethers / Q000138:chemical synthesis*; D020560:Proteobacteria / Q000201:enzymology*; D011621:Pteridines / Q000378:metabolism; D014867:Water / Q000737:chemistry
D003067:Coenzymes; D008667:Metalloproteins; D000090006:Molybdenum Cofactors; D010088:Oxidoreductases; D010636:Phenols; D010647:Phenyl Ethers; D011621:Pteridines; D014867:Water; C434346:1,2,4,5-tetrahydroxybenzene; C031538:phenyl ether; C022261:molybdopterin; C401266:pyrogallol hydroxyltransferase