Descrição
"Abstracts of papers presented at the 232nd American Chemical Society National Meeting" The potential of laccase enzymes for polymerizing, crosslinking and
functionalizing various compounds was studied extensively and increasing
interest has been focused on the application of this enzyme as a new
biocatalyst in organic synthesis.[1-6] Laccases (EC 1.10.3.2) are a class of
multi-copper-containing oxidoreductase enzymes able to catalyze the
transformation of various aromatic compounds, specifically phenols and
anilines, through the formation of a free cation radical after the transfer of a
single electron to laccase. The radical can further react on non-enzymatic
oxidation polymerizing various halogen, alkyl-, alkoxy-substituted anilines
and phenols.[7-8] The phenolic derivatives resulting in the production of
polymeric aggregates are usually less soluble and much stable than their
parent compounds.[9,10] Unfortunately the relatively short catalytic lifetime of
the laccases in the polymerization processes and the mass transfer
limitations, restrict their applications. This effect can be attributed to the
inactivation of the enzyme active site due to phenoxy radicals and polymers
produced during enzyme treatment.[11]
To overcome this limitations the use of ultrasound, under proper conditions,
has shown to enhance significantly the mass transfer as well as the structure
stability, substrate binding, and activity of the enzyme.[12,13] Ultrasound alone
or in combination with other methods is known to enhance a wide variety of
chemical and physical processes, mainly due to the phenomenon known as
cavitation in a liquid medium that is the growth and explosive collapse of
microscopic bubbles.[14-16] These localized ‘‘hot spots’’ generate high local
temperature and pressure rise, capable of decompose water to hydrogen
atoms and hydroxyl radicals and of break several chemical bonds.[17,18]
Therefore in this work laccase from Trametes villosa was tested in
combination with ultrasound to improve the radical polymerization of
catechol. A solid-state “in situ” sono-enzymatic synthesis of poly(catechol)
was also performed by coloration of wool. The results were analyzed by
spectrophotometric and HPLC analyses.
; Basto, Carlos 
