H2O2 recycling during oxidation of the arylglycerol beta-aryl ether lignin structure by lignin peroxidase and glyoxal oxidase.
Oxidative C alpha-C beta cleavage of the arylglycerol beta-aryl ether lignin model 1-(3,4-dimethoxy-phenyl)-2-phenoxypropane-1,3-diol (I) by Phanerochaete chrysosporium lignin peroxidase in the presence of limiting H2O2 was enhanced 4-5-fold by glyoxal oxidase from the same fungus. Further investigation showed that each C alpha-C beta cleavage reaction released 0.8-0.9 equiv of glycolaldehyde, a glyoxal oxidase substrate. The identification of glycolaldehyde was based on 13C NMR spectrometry of reaction product obtained from beta-, gamma-, and beta,gamma-13C-substituted I, and quantitation was based on an enzymatic NADH-linked assay. The oxidation of glycolaldehyde by glyoxal oxidase yielded 0.9 oxalate and 2.8 H2O2 per reaction, as shown by quantitation of oxalate as 2,3-dihydroxyquinoxaline after derivatization with 1,2-diaminobenzene and by quantitation of H2O2 in coupled spectrophotometric assays with veratryl alcohol and lignin peroxidase. These results suggest that the C alpha-C beta cleavage of I by lignin peroxidase in the presence of glyoxal oxidase should regenerate as many as 3 H2O2. Calculations based on the observed enhancement of LiP-catalyzed C alpha-C beta cleavage by glyoxal oxidase showed that approximately 2 H2O2 were actually regenerated per cleavage of I when both enzymes were present. The cleavage of arylglycerol beta-aryl ether structures by ligninolytic enzymes thus recycles H2O2 to support subsequent cleavage reactions.
Hammel
K E
KE
USDA Forest Products Laboratory, Madison, Wisconsin 53705.
Mozuch
M D
MD
Jensen
K A
KA
Kersten
P J
PJ
D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D005658:Fungi / Q000201:enzymology*; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008031:Lignin / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008954:Models, Biological; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000378:metabolism*
D008031:Lignin; D006861:Hydrogen Peroxide; D000429:Alcohol Oxidoreductases; C052371:glyoxal oxidase; D010544:Peroxidases; C042858:lignin peroxidase