Laccase catalysed conjugation of catechin with poly(allylamine): Solvent effect

The Trametes versicolor laccase catalysed the synthesis of poly(allylamine) catechin conjugate by conjugation of catechin with poly(allylamine) was studied in 11 different solvents in order to deduce the solvent effect through an attempt to correlate the initial reaction rate with solvent properties such as hydrophobicity (log P), water solubility (log S-W), electron pair acceptance (E-T(N)) and donation abilities (D-N(N)), polarisibility and dielectric constant. The initial rate was found to exhibit reasonable correlation with log P, log S-W, E-T(N) + D-N(N), polarisibility and dielectric constant. The probable explanation for the deviation has been put forward based on established hypothesis. The study revealed, in general that polar solvents favour the initial reaction rate. The organic solvent interferes neither with the laccase-substrate binding process nor with the catalytic mechanism. The contribution of the substrate-solvent interactions to enzyme kinetics was accounted by replacing the substrate concentration by thermodynamic activities. (C) 2009 Elsevier B.V. All rights reserved.