Cleavage of β aryl ether linkage in nonphenolic lignin model compound by manganese peroxidase

A substrate, 3-hydroxy-2-(4-methylumbelliferyl) -1-phenyl-1-propanone, which release fluorescent 4-methylumbelliferone by the cleavage of the ether bond, was synthesized. At first, using this model comound, 140 strains of white-rot fungi were screened and 7 strains showed positive fluorescence. Under the same culture condition, known white-rot fungi, Phanerochaete chrysosporium and Trametes versicolor did not show any fluorescence. One of the 7 strains, a white-rot fungus IO-427, was selected and the model compound was treated in vitro with the culture filtrate of the fungus. The ether linkage of model compound was cleaved quantitatively. By analyzing the culture filtrate of the fungus, we found that manganese peroxidase (MnP) was involved in the reaction. The model compound was treated with MnP from Phanerochaete sordida YK-624 with the low molecular weight fungal products of white-rot fungus IO-427 or with MnSO4 and Tween 80. Only the combination of MnP and fungal products of the fungus IO-427 showed the quantitative cleavage of the ether linkage.