REDUCTIONS CATALYZED BY A QUINONE AND PEROXIDASES FROM PHANEROCHAETE-CHRYSOSPORIUM

A quinone produced from veratryl alcohol by lignin peroxidase from the white rot fungus Phanerochaete chrysosporium was tested for its abili ty to mediate reduction, The quinone (2-hydroxymethyl-5-methoxy-1,4-be nzoquinone), reduced chemically or by cellobiose:quinone reductase iso lated from cultures of the fungus, mediated the reduction of cytochrom e c in reactions containing either Mn(III), a manganese-dependent pero xidase, Mn(II) and H2O2, or lignin peroxidase and H2O2, Formation of t he semiquinone, the species responsible for reducing cytochrome c, was observed by electron spin resonance spectroscopy in these reactions. The production of the quinone was observed in the extracellular fracti on of cultures grown under nutrient nitrogen-deficient conditions (2.4 mM ammonium tartrate) for over 10 days, starting on Day 2, but not un der nutrient nitrogen-sufficient conditions. These results suggest tha t a quinone produced by lignin peroxidase can serve as a physiological mediator of reductive reactions catalyzed by the fungal peroxidases. (C) 1995 Academic Press, Inc.