Laccase-catalyzed polymerization of tyrosine and tyrosine-containing pep-tides was studied in the presence and absence of ferulic acid (FA). Advanced spectroscopic methods such as MALDI-TOF MS, EPR, FTIR microscopy and HPLC-fluorescence, as well as more conventional analyt-ical tools: oxygen consumption measurements and SDS⁄PAGE were used in the reaction mechanism studies. Laccase was found to oxidize tyrosine and tyrosine-containing peptides, with consequent polymerization of the compounds.
