Oxalate-dependent reductive activity of manganese peroxidase from Phanerochaete chrysosporium.
The mechanism of oxalate-dependent reductive activity of a manganese-dependent peroxidase (MnP) from Phanerochaete chrysosporium was investigated. Ferric iron reduction was demonstrated in reaction mixtures containing Mn-peroxidase, Mn2+, oxalate, H2O2, ferric chloride, and 1,10-phenanthroline. Only catalytic amounts of H2O2 were required. Oxygen consumption was also observed in reaction mixtures containing Mn-peroxidase, Mn2+, oxalate, and H2O2 and was inhibited by the addition of ferric iron. Electron spin resonance studies, using the spin traps 5,5-dimethyl-1-pyrroline-N-oxide and alpha-4-pyridyl-1-oxide-N-t-butylnitrone were used to obtain evidence for the production of the formate radical (CO2.-) and superoxide (O2.-) in a reaction mixture containing Mn2+, oxalate and H2O2. It was concluded that both CO2.- (anaerobic conditions) and O2.- (aerobic conditions) could reduce ferric iron. The dismutation of some O2.- would produce H2O2 to provide a constant supply of H2O2.
Khindaria
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Biotechnology Center, Utah State University, Logan 84322-4705.
Grover
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TA
Aust
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SD
D000332:Aerobiosis; D000363:Agaricales / Q000201:enzymology*; D000693:Anaerobiosis; D003374:Coumarins; D004578:Electron Spin Resonance Spectroscopy; D007700:Kinetics; D010070:Oxalates / Q000378:metabolism* / Q000494:pharmacology; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000378:metabolism*; D013113:Spin Labels
C064384:4',5'-dihydroxy-7-methoxy-4-phenyl-5,2'-oxidocoumarin; D003374:Coumarins; D010070:Oxalates; D013113:Spin Labels; D010544:Peroxidases; C051129:manganese peroxidase