TRANSFORMATION OF 2-HYDROXYDIBENZOFURAN BY LACCASES OF THE WHITE-ROT FUNGI TRAMETES-VERSICOLOR AND PYCNOPORUS-CINNABARINUS AND CHARACTERIZATION OF OLIGOMERIZATION PRODUCTS

Laccase, a ligninolytic enzyme, was secreted by each of the white rot fungi Trametes versicolor and Pycnoporus us cinnabarinus during growth in a nitrogen-rich medium ender agitated conditions. After addition o f 2-hydroxydibenzofuran to cell-free supernatants of the cultures, yel low precipitates were formed. These precipitates were poorly soluble i n water and therefore readily separated from the supernatant. The prod ucts formed were more hydrophobic than the substrate, as indicated by their longer retention times on a reverse phase high-performance liqui d chromatography column. Mass spectrometric analysis of the purified p roducts indicated the formation of oligomers. Analysis of the mixture of products by gas chromatography and mass spectrometry after derivati zation with diazomethane suggested the formation of at least three dim eric and nine trimeric, products. Carbon-carbon and carbon-oxygen bond s were identified in the dimers and trimers, respectively. The nuclear magnetic resonance spectrum of the main dimer suggested coupling of t he two monomers at the carbon one position.