62
H
OH
H
OH
OH
H
OH
H
CHpH
H
H
OH
f3-D-glucose
(hexose)
H
H
NH
I
C=O
I
CH3
o
o
N-acetyl-f3-D-glucosamine
(aminosugar)
H
OH
OH
H
H
OH
OH
H
Fig. 2.14. Structure of some common monosaccharides
H
OH
H
OH
S. Pantoja· S. Wakeham
H
H
H
OH
f3-D-ribose
(pentose)
H
OH
CH
H
a-D-fucose
(deoxy sugar)
o
OH
H
o
H
OH
degraded at the 1,6-linkage by anaerobic marine bacteria (Arnosti and Repeta 1994).
Other evidence suggests that enzymatic hydrolysis of macromolecular carbohydrates
is, in general, a fast reaction with some substrates, and rates of hydrolysis do not necessarily correlate with the molecular weight of substrates (Arnosti et al. 1994).
2.2.4
Lignin and Other CuO-Oxidation Products
2.2.4.1
Lignin
Lignin is a phenolic macromolecule that is biosynthesized by vascular land plants
(Sarkanen and Ludwig 1971). Accounting for up to 30 wt% of woody tissues, its functions are both structural and protective. The lignin-hemicellulose complex associated
with cellulose microfibrils imposes a structural rigidity to wood, and lignin protects
cell wall polysaccharides from microbial attack (Goodwin and Mercer 1972; Kirk and
Farrell 1987). Because photosynthesis by vascular plants represents over half of the
global primary productivity (Fig. 2.2), lignin is a major component of the global biogeochemical cycle and may be a significant source of organic matter to marine envi-
H
OH
H
OH
OH
H
OH
H
CHpH
H
H
OH
f3-D-glucose
(hexose)
H
H
NH
I
C=O
I
CH3
o
o
N-acetyl-f3-D-glucosamine
(aminosugar)
H
OH
OH
H
H
OH
OH
H
Fig. 2.14. Structure of some common monosaccharides
H
OH
H
OH
S. Pantoja· S. Wakeham
H
H
H
OH
f3-D-ribose
(pentose)
H
OH
CH
H
a-D-fucose
(deoxy sugar)
o
OH
H
o
H
OH
degraded at the 1,6-linkage by anaerobic marine bacteria (Arnosti and Repeta 1994).
Other evidence suggests that enzymatic hydrolysis of macromolecular carbohydrates
is, in general, a fast reaction with some substrates, and rates of hydrolysis do not necessarily correlate with the molecular weight of substrates (Arnosti et al. 1994).
2.2.4
Lignin and Other CuO-Oxidation Products
2.2.4.1
Lignin
Lignin is a phenolic macromolecule that is biosynthesized by vascular land plants
(Sarkanen and Ludwig 1971). Accounting for up to 30 wt% of woody tissues, its functions are both structural and protective. The lignin-hemicellulose complex associated
with cellulose microfibrils imposes a structural rigidity to wood, and lignin protects
cell wall polysaccharides from microbial attack (Goodwin and Mercer 1972; Kirk and
Farrell 1987). Because photosynthesis by vascular plants represents over half of the
global primary productivity (Fig. 2.2), lignin is a major component of the global biogeochemical cycle and may be a significant source of organic matter to marine envi-