ENZYMATIC CO-POLYMERIZATION OF LIGNIN WITH LOW-MOLECULAR-MASS COMPOUNDS

The oxidoreductive enzyme laccase (E.C.1.10.3.2.) isolated from a cult ure medium of white-rot fungus Trametes versicolor transformed lignin preparations solubilized in a dioxane-H2O (7:3) mixture. The obvious n et result of lignin transformation was an increase in molecular mass. A superoxide radical was found in the reaction mixture during lignin i ncubation with laccase. It appeared that a change in the reaction medi um or in the lignin molecule instigated by laccase could lead to polym erization after the lignin molecules had crossed a dialysis membrane a nd were separated from the enzyme. Two possible mechanisms are suggest ed, either diffusion of an activated oxygen species or diffusion of pr imed lignin molecules. Laccase was able to co-polymerize lignin with l ow-molecular-mass compounds of different origins, particularly with ar omatics containing either carboxyl or isocyanate groups, as well as ac rylamide - an aliphatic monomer containing a vinyl group.