Comparison of structure and activities of peroxidases from Coprinus cinereus, Coprinus macrorhizus and Arthromyces ramosus.

Initial structural and kinetic data suggested that peroxidases from Coprinus cinereus, Coprinus macrorhizus and Arthromyces ramosus were similar. Therefore they were characterized more fully. The three peroxidases were purified to RZ 2.5 and showed immunochemical identity as well as an identical M(r) of 38,000, pI about 3.5 and similar amino acid compositions. The N-termini were blocked for amino acid sequencing. The peroxidases had similar retention volumes by anion-exchange and gel-filtration chromatography. All peroxidases showed multiple peaks by Concanavalin A-Sepharose chromatography. The Concanavalin A-Sepharose profiles were different and depended furthermore on a fermentation batch. Tryptic peptide maps were very similar except for one peptide. This peptide contained an N-linked glycan composed of varying ratios of glucosamine and mannose for the three peroxidases. Rate constants and their pH dependence were the same for the three peroxidases using guaiacol or iodide as reducing substrates. We conclude that peroxidases from Coprinus cinereus, Coprinus macrorhizus and Arthromyces ramosus are most likely identical in their amino acid sequences, but deviate in glycosylation which, apparently, has no influence on the reaction rates of the enzyme. We suggest, that the Coprinus fungi express one peroxidase only in contrast to the lignin-degrading white-rot Basidiomycetes, which produce multiple peroxidase isozymes.