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Prediction model based on decision tree analysis for laccase mediators.

Enzyme and microbial technology (2012-12-04)
Fabiola Medina, Sergio Aguila, Maria Camilla Baratto, Andrea Martorana, Riccardo Basosi, Joel B Alderete, Rafael Vazquez-Duhalt
ABSTRACT

A Structure Activity Relationship (SAR) study for laccase mediator systems was performed in order to correctly classify different natural phenolic mediators. Decision tree (DT) classification models with a set of five quantum-chemical calculated molecular descriptors were used. These descriptors included redox potential (ɛ°), ionization energy (E(i)), pK(a), enthalpy of formation of radical (Δ(f)H), and OH bond dissociation energy (D(O-H)). The rationale for selecting these descriptors is derived from the laccase-mediator mechanism. To validate the DT predictions, the kinetic constants of different compounds as laccase substrates, their ability for pesticide transformation as laccase-mediators, and radical stability were experimentally determined using Coriolopsis gallica laccase and the pesticide dichlorophen. The prediction capability of the DT model based on three proposed descriptors showed a complete agreement with the obtained experimental results.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
2-Ethoxyphenol, 98%
Sigma-Aldrich
Vanillic acid, ≥97%, FG
Sigma-Aldrich
Bis(5-chloro-2-hydroxyphenyl)methane, 95%
Sigma-Aldrich
Syringaldazine, 98%
Sigma-Aldrich
Vanillic acid, 97%
Sigma-Aldrich
Syringaldazine, indicator for laccase and peroxidase activity
Sigma-Aldrich
Sinapic acid, ≥98%, powder
Supelco
Sinapic acid, matrix substance for MALDI-MS, ≥99.0% (T)
Sigma-Aldrich
Vanillic acid, purum, ≥97.0% (HPLC)
Supelco
Vanillic acid, certified reference material, TraceCERT®, Manufactured by: Sigma-Aldrich Production GmbH, Switzerland
Supelco
Sinapic acid, matrix substance for MALDI-MS, ≥99.5%, Ultra pure
Sigma-Aldrich
3-Methoxycatechol, 99%
Sigma-Aldrich
Laccase from Agaricus bisporus, powder, deep brown, ≥4 U/mg
Sigma-Aldrich
Syringaldehyde, ≥98%, FG
Sigma-Aldrich
3′,5′-Dimethoxy-4′-hydroxyacetophenone, 97%
Sigma-Aldrich
Syringaldehyde, 98%
Sigma-Aldrich
Laccase from Rhus vernicifera, crude acetone powder, ≥50 units/mg solid
Sigma-Aldrich
Laccase from Trametes versicolor, powder, light brown, ≥0.5 U/mg