3. Results and discussion
Laccase-mediated biografting of PCA on coconut fibers was pro-
ceeded in three steps. Lignin free radicals were generated by laccase
in the first step. In the second step, radical cation was formed due
to the electron transfer process, which was followed by a quick
removal of hydrogen ion (deprotonation) and this resultin the gen-
eration of phenoxy radical. The formation of phenoxy radical is a
rate determining step in the laccase catalyzed oxidation of pheno-
lic compounds. Phenoxy radical of p-coumaric acid formed in the
second step has very less stability. In the last step, phenoxy radi-
cals coupled with the lignin radicals to get stabilized and results in
biografting (Fig. 1) [26].
3.1. Optimization of reaction parameters
The amount of reactants affects the enzymatic reactions to a
great extent. So, PCA concentration, laccase concentration and the
incubation period were optimized in laccase-mediated biograft-
ing. Different concentrations of phenol i.e. 2.5%, 3.5%, 4.5% and
3. Results and discussionLaccase-mediated biografting of PCA on coconut fibers was pro-ceeded in three steps. Lignin free radicals were generated by laccasein the first step. In the second step, radical cation was formed dueto the electron transfer process, which was followed by a quickremoval of hydrogen ion (deprotonation) and this resultin the gen-eration of phenoxy radical. The formation of phenoxy radical is arate determining step in the laccase catalyzed oxidation of pheno-lic compounds. Phenoxy radical of p-coumaric acid formed in thesecond step has very less stability. In the last step, phenoxy radi-cals coupled with the lignin radicals to get stabilized and results inbiografting (Fig. 1) [26].3.1. Optimization of reaction parametersThe amount of reactants affects the enzymatic reactions to agreat extent. So, PCA concentration, laccase concentration and theincubation period were optimized in laccase-mediated biograft-ing. Different concentrations of phenol i.e. 2.5%, 3.5%, 4.5% and
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