Laccase is a multicopper
oxidase that catalyzes the oxidation of phenolic compounds.
Laccase can be used in bioremediation, beverage (wine, fruit juice, and beer) processing,
ascorbic acid determination,
sugar beet
pectin gelation baking, and as a biosensor. Recently, the antiproliferative activity of
laccase toward
tumor cells has been reported. Because of the potential applications of this
enzyme, the efforts for enhancing and stabilizing its activity have increased. Thus, the PEGylation of
laccase can be an alternative. PEGylation is the covalent attachment of one or more molecules of methoxy poly(
ethylene glycol) (
mPEG) to a
protein. Normally, during the PEGylation reaction, the activity is reduced but the stability increases; thus, it is important to minimize the loss of activity. In this work, the effects of molar ratio (1:4, 1:8, and 1:12), concentration of
laccase (6 and 12 mg/ml), reaction time (4 and 17 h), molecular weight, and type of
mPEG (20, 30, 40 kDa and 40 kDa-branched) were analyzed. The activity was measured using three substrates:
ABTS,
2,6-dimethoxyphenol, and
syringaldazine. The best conditions for
laccase PEGylation were 12 mg/ml of
laccase, molar ratio 1:4, and 4 h reaction time. Under these conditions, the
enzyme was able to maintain nearly 100% of its enzymatic activity with
ABTS. The PEGylation of
laccase has not been extensively explored, so it is important to analyze the effects of this bioconjugation in route to produce a robust modified
enzyme.