Table 7.1 List of enzymes that assist the biomass degradation and their mechanism of action
Enzyme
Mechanism of action
Reference
Lignin degrading enzymes
Laccase
(1.10.3.2)
It catalyzes the oxidation reactions that lead to the free
radical formation which can be intermediate substrates
Li et al.
(2018)
Mn peroxidase
(1.11.1.13)
It acts only on the phenolic structures of lignin
Kinnunen
et al. (2017)
Lignin peroxidase
(1.11.1.14)
It reacts in the presence of hydrogen peroxide with
catalysis of the oxidative depolymerization of
non-phenolic lignin, β-O-4 non-phenolic lignin, and
phenolics
Houtman
et al. (2018)
Versatile peroxidase
(1.11.1.16)
It oxidizes the substrates of Mn peroxidase and lignin
peroxidase
Kinnunen
et al. (2017)
Cellulose degrading enzymes
Endoglucanase
(3.2.1.4)
Random catalysis of internal cellulose chain by releasing cellulose subunits, i.e., cellobiose and cellooligosaccharides
Pamella et al.
(2017)
Exoglucanase
(3.2.1.91)
Catalysis of cellulose chains specifically at terminal part
by releasing the cellulose subunits
Parafati et al.
(2017)
β-Glucosidase
(3.2.1.21)
Catalysis of cellulose subunits which release the glucose
and other metabolites
Boudabbous
et al. (2017)
Hemicellulose degrading enzymes
α-LArabinofuranosidase
(3.2.1.55)
Catalysis of terminal α-L-arabinofuranoside which can
be converted into α-L-arabinosides
Bastos et al.
(2018)
α-D-Glucuronidase
(3.2.1.131)
Catalysis of α-1,2 glycosidic bond of hemicellulose
which converts into D-glucuronic acid, 4-O-methyl-Dglucuronic acid, and D-xylose
Manavalan
et al. (2015)
Acetyl xylan esterase
(3.1.1.72)
Catalysis with deacetylation reaction of xylans and xylooligosaccharides
Komiya et al.
(2017)
β-xylosidase
(3.2.1.37)
Catalysis of xylobiose which convert the D-xylose
Bastos et al.
(2018)
Endo xylanase
(3.2.1.8)
Catalysis of β-1,4-xylan which convert xylose
Manavalan
et al. (2015)
Ferulic acid esterase
(3.1.1.71)
Catalysis of COOH- bonds of feruloyl-polysaccharide
which converts into ferulic acid and polysaccharide
Manavalan
et al. (2015)
Accessory enzymes
Cellobiose dehydrogenase
(1.1.99.18)
It reduces aromatic radicals preventing
repolymerization, demethoxylation, or hydroxylation of
nonphenolic lignin and reduction of precipitated MnO 2
Ma et al.
(2017)
Aryl-alcohol oxidase
(1.1.3.7)
Aromatic alcohols oxidized to aldehydes, which generates the H 2 O 2
Houtman
et al. (2018)
Glyoxal oxidase
(1.2.3.15)
Glyoxal oxidized to glyoxylic acid, which produces the
H 2 O 2
Manavalan
et al. (2015)
Oxalate decarboxylase (4.1.1.2)
It degrades the oxalic acid and converted into CO 2
Manavalan
et al. (2015)
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189
Enzyme
Mechanism of action
Reference
Lignin degrading enzymes
Laccase
(1.10.3.2)
It catalyzes the oxidation reactions that lead to the free
radical formation which can be intermediate substrates
Li et al.
(2018)
Mn peroxidase
(1.11.1.13)
It acts only on the phenolic structures of lignin
Kinnunen
et al. (2017)
Lignin peroxidase
(1.11.1.14)
It reacts in the presence of hydrogen peroxide with
catalysis of the oxidative depolymerization of
non-phenolic lignin, β-O-4 non-phenolic lignin, and
phenolics
Houtman
et al. (2018)
Versatile peroxidase
(1.11.1.16)
It oxidizes the substrates of Mn peroxidase and lignin
peroxidase
Kinnunen
et al. (2017)
Cellulose degrading enzymes
Endoglucanase
(3.2.1.4)
Random catalysis of internal cellulose chain by releasing cellulose subunits, i.e., cellobiose and cellooligosaccharides
Pamella et al.
(2017)
Exoglucanase
(3.2.1.91)
Catalysis of cellulose chains specifically at terminal part
by releasing the cellulose subunits
Parafati et al.
(2017)
β-Glucosidase
(3.2.1.21)
Catalysis of cellulose subunits which release the glucose
and other metabolites
Boudabbous
et al. (2017)
Hemicellulose degrading enzymes
α-LArabinofuranosidase
(3.2.1.55)
Catalysis of terminal α-L-arabinofuranoside which can
be converted into α-L-arabinosides
Bastos et al.
(2018)
α-D-Glucuronidase
(3.2.1.131)
Catalysis of α-1,2 glycosidic bond of hemicellulose
which converts into D-glucuronic acid, 4-O-methyl-Dglucuronic acid, and D-xylose
Manavalan
et al. (2015)
Acetyl xylan esterase
(3.1.1.72)
Catalysis with deacetylation reaction of xylans and xylooligosaccharides
Komiya et al.
(2017)
β-xylosidase
(3.2.1.37)
Catalysis of xylobiose which convert the D-xylose
Bastos et al.
(2018)
Endo xylanase
(3.2.1.8)
Catalysis of β-1,4-xylan which convert xylose
Manavalan
et al. (2015)
Ferulic acid esterase
(3.1.1.71)
Catalysis of COOH- bonds of feruloyl-polysaccharide
which converts into ferulic acid and polysaccharide
Manavalan
et al. (2015)
Accessory enzymes
Cellobiose dehydrogenase
(1.1.99.18)
It reduces aromatic radicals preventing
repolymerization, demethoxylation, or hydroxylation of
nonphenolic lignin and reduction of precipitated MnO 2
Ma et al.
(2017)
Aryl-alcohol oxidase
(1.1.3.7)
Aromatic alcohols oxidized to aldehydes, which generates the H 2 O 2
Houtman
et al. (2018)
Glyoxal oxidase
(1.2.3.15)
Glyoxal oxidized to glyoxylic acid, which produces the
H 2 O 2
Manavalan
et al. (2015)
Oxalate decarboxylase (4.1.1.2)
It degrades the oxalic acid and converted into CO 2
Manavalan
et al. (2015)
7 Strategies to Improve Remediation Technology Using Fungi
189