In vitro degradation of a polymeric dye (Poly R-478) by manganese peroxidase

The aim of this study is the evaluation of the enzymatic action of the lign inolytic enzyme manganese peroxidase (MnP), through a suitable addition of H2O2, as a feasible system for the in vitro degradation of complex structur es. For this purpose, a highly recalcitrant polymeric dye (Poly R-478) was selected as a model compound. An amperometric technique was used to determi ne the H2O2 requirement in the clecolorization by nonpurified MnP. Two H2O2 supply strategies-fed-batch (every hour) or semicontinuous (every 5 min)-w ere applied. The addition of H2O2 in pulses led to a limited decolorization after the pulses and the instantaneous consumption or decomposition of H2O 2. Therefore, this way of addition may limit the actual H2O2 concentration in the reaction mixture. In contrast, the semicontinuous strategy maintaine d lower and prolonged concentrations of H2O2, which allowed a clearly great er decolorization (48% after 2 h). In addition, the effect of Mn+2 concentr ation on the clecolorization efficiency was investigated to establish the o ptimal application of the MnP-oxidative system. The enzymatic treatment pro voked not only the destruction of the chromophoric groups but also a notice able breakdown of the chemical structure of the dye. In experiments with pu re enzyme, MnP proved to be the main factor responsible for the dye clecolo rization. (C) 2001 John Wiley & Sons, Inc.