Oxidative cross-linking of wheat arabinoxylans by manganese peroxidase. Comparison with laccase and horseradish peroxidase. Effect of cysteine and tyrosine on gelation

The potential of manganese peroxidase (MnP) from Phanerochaete chrysosporiu m to cross-link wheat arabinoxylans, and to covalently link cysteine and ty rosine to the ferulic acid esterified on arabinoxylans, was investigated. M nP was able to gel arabinoxylans by oxidative coupling of their feruloyl gr oups, with concominant formation of dehydrodimers of ferulic acid. Whereas at high concentrations cysteine delayed gelation, at low concentrations it had no effect. Tyrosine did not affect gelation, but it accelerated the con sumption of ferulic acid. The MnP was compared to laccase from Pycnoporus c innabarinus and the couple hydrogen peroxide/horseradish peroxidase (H2O2/P OD). (C) 1999 Society of Chemical Industry.