DISULFIDE BONDS AND GLYCOSYLATION IN FUNGAL PEROXIDASES

Four conserved disulfide bonds and N-linked and O-linked glycans of ex tracellular fungal peroxidases have been identified from studies of a lignin and a manganese peroxidase from Trametes versicolor, and from C oprinus cinereus peroxidase (CIP) and recombinant C. cinereus peroxida se (rCIP) expressed in Aspergillus oryzae. The eight cysteine residues are linked 1-3, 2-7, 4-5 and 6-8, and are located differently from th e four conserved disulfide bridges present in the homologous plant per oxidases. CIP and rCIP were identical in their, glycosylation pattern, although the extent of glycan chain heterogeneity depended on the fer mentation batch. CIP and rCIP have one N-linked glycan composed only o f GlcNAc and Man at residue Asn142, and two O-linked glycans near the C-terminus. The major glycoform consists of single Man residues at Thr 331 and at Ser338. T. versicolor lignin isoperoxidase TvLP10 contains a single N-linked glycan composed of (GlcNAc)(2)Man(5) bound to Asn103 , whereas (GlcNAc)(2)Man(3) was found in T. versicolor manganese isope roxidase TvMP2 at the same position. In addition, mass spectrometry of the C-terminal peptide of TvMP2 indicated the presence of five Man re sidues in O-linked glycans. No phosphate was found in these fungal per oxidases.