Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: KEGG:D02011 (FAD)
 5,530 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Several catalytic properties of the FAD enzyme cellobiose:quinone oxidoreductase (CBQ) and the heme/FAD enzyme, cellobiose oxidase (CBO) have been investigated and compared. Dichlorophenol-indophenol was found to be a very good electron acceptor for cellobiose oxidation by both enzymes. The optimal pH value for this oxidation with dichlorophenol-indophenol as a co-substrate was observed around pH 4 for both enzymes. The turnover numbers of this reaction were also very similar. The Km values for cellobiose oxidation were identical, whereas the Km for CBO with dichlorophenol-indophenol is lower than that of CBQ. Atmospheric oxygen is a very poor electron acceptor for both CBO and CBQ, however, CBO can utilize cytochrome c as an effective electron acceptor, while CBQ cannot. The specific activity of CBO for cytochrome c is thus about 200-times higher than for oxygen. Thus, one way to distinguish the two enzymes is by the cytochrome-c-reducing ability of CBO. Therefore, we propose that the nomenclature for CBO is tentatively changed to cellobiose:cytochrome c oxidoreductase until a rational name can be installed. Both enzymes have radical-reducing activities. The cation radical, derived from 1,2,4,5-tetramethoxybenzene, was reduced by both enzymes at almost the same reaction rate. The phenoxyradical produced by lignin peroxidase, catalyzing the oxidation of acetosyringon, was also reduced by both enzymes. The reduction of phenoxyradicals formed by phenoloxidases (lignin peroxidases, as well as laccases) may be important in preventing repolymerization reactions which we suggest would significantly facilitate lignin degradation.
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PMID:A comparison of the catalytic properties of cellobiose:quinone oxidoreductase and cellobiose oxidase from Phanerochaete chrysosporium. 132 Oct 38

The mechanism of redox interactions between the heme-enzyme, lignin peroxidase (LiP), and the FAD-enzyme, cellobiose:quinone oxidoreductase (CBQ) (EC 1.1.5.1), was investigated under various conditions. Veratryl alcohol oxidation by LiP was inhibited by CBQ in the presence of cellobiose. Lineweaver-Burk plots at various CBQ concentrations suggest that this inhibition is non-competitive. The oxidation rate of the reduced CBQ (FADH2) by LiP plus H2O2 increased significantly only in the presence of veratryl alcohol. Furthermore, the cation radical derived from 1,2,4,5-tetramethoxybenzene was reduced by CBQ in the presence of cellobiose. It is concluded from these results that CBQ can reduce aromatic cation radicals and that veratryl alcohol acts as a radical mediator of the redox interactions between LiP and CBQ.
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PMID:Mechanisms of redox interactions between lignin peroxidase and cellobiose:quinone oxidoreductase. 195 97