Triiodide reduction by cellobiose:quinone oxidoreductase of Phanerochaete chrysosporium.
Cellobiose:quinone oxidoreductase (CBQase) in the presence of cellobiose inhibits peroxidase-catalyzed oxidation of iodide to triiodide (I3). This inhibition is due to the two-electron reduction of I3- by CBQase. The apparent Km of I3- for this reaction is 120 microM and the specific activity is 57 mumol.min-1.mg-1. A proposed mechanism for I3- reduction by CBQase involves initial reduction of the flavin moiety by cellobiose to produce a dihydroflavin. This is followed by the substitution of one of the iodine atoms of I3- at the C(4a)-position of dihydroflavin to generate C(4a)-iododihydroflavin and two iodide ions. The C(4a)-iododihydroflavin eliminates HI to regenerate the oxidized CBQase.
Bao
W J
WJ
Department of Chemical and Biological Sciences, Oregon Graduate Institute of Science and Technology, Beaverton, OR 97006-1999.
Renganathan
V
V
D001487:Basidiomycota / Q000201:enzymology*; D002237:Carbohydrate Dehydrogenases / Q000378:metabolism*; D002384:Catalysis; D002475:Cellobiose / Q000737:chemistry; D005415:Flavins / Q000737:chemistry; D007454:Iodides / Q000737:chemistry*; D010084:Oxidation-Reduction; D009195:Peroxidase
D005415:Flavins; D007454:Iodides; D002475:Cellobiose; D002237:Carbohydrate Dehydrogenases; C019859:cellobiose-quinone oxidoreductase; D009195:Peroxidase