Part D | 22.2
548 Part D Marine Algal Biotechnology
Table 22.2 (continued)
Order
Species
M/G value
References
Laminariales
Laminaria pallida
2.33 (stipes)
[22.48]
Laminaria digitata
1.45
[22.11]
1:352:08 (blade)
[22.29]
Laminaria longicruris
1:442:17
Agarum cribosum
1.30 (blade)
Macrocystis pyriphera
1:381:70
[22.7, 11, 29, 32, 49]
1.52 (frond)
1.02 (stipes)
1.41 (blade)
Macrocystis boryana
0.79
[22.11]
Lessonia trabeculata
1.73
[22.50]
Lessonia variegata
1.95
[22.26]
Ecklonia radiata
1.60
Scytosiphonales
Scytosiphon lomentaria
1.15; 0.67
the high-M and low-M alginates consist mainly of
homopolymeric blocks (GG, MM), which are almost
directly connected and contain few or no heteropolymeric blocks. It was also found that young algal tissues
are rich in M-blocks, and that the difference between
the alginates from different species was mainly due to
the contribution of the older parts of thalli [22.11].
22.2.2 Sulfated Galactans
Sulfated galactans are common cell wall matrix
polysaccharides of green (Clorophyta) and red (Rhodophyta) algae. They are polymers of partially sulfated
ˇ-D- sand/or ˛-D(L)-galactopyranosyl (Galp) units.
Sulfated galactans from cell walls of green algae (genera Codium and Bryopsis) were reported to
be both homo and heteropolysaccharides, depending on the species [22.17, 19, 20, 22, 51]. Polysaccharides isolated from Codium isthmocladum [22.20] and
Codium yezoense [22.17, 52] are sulfated homogalactans containing similar backbones, composed mainly
of (1 ! 3)-linked ˇ-D-Galp units and short oligosaccharide side chains bound at O-6. The units were
sulfated mainly at O-4 and rarely at O-6, and nonreducing terminal residues were pyruvylated forming
cyclic 3,4-ketals. Sulfated galactan isolated from Bryopsis plumosa (Bryopsidales, Chlorophyta) consist of
a (1 ! 3)-linked ˇ-D-Galp partially sulfated on O6 and substituted with pyruvic acid, forming 4,6-ketals [22.19]. A branched sulfated (1 ! 3), (1 ! 6)ˇ-D-galactan was isolated from Codium fragile. This
polysaccharide has a (1 ! 3)-linked partially 4-O-sulfated ˇ-D-Galp backbone with some 3,4-pyruvated ˇD-Galp stubs at O-6 positions [22.21]. By contrast,
galactans isolated from Codium fragile [22.51] and
Codium cylindricum [22.22] contain other sugar units –
arabinose and glucose, respectively. Nevertheless, the
!3)-ˇ-D-Galp4S-(1! units still predominate in these
polysaccharides. Water-soluble highly sulfated arabinans, galactans, and/or arabinogalactans were isolated
from Codium fragile and Codium vermilara [22.18].
These polysaccharides are composed of (1 ! 3)-linked
ˇ-D-Galp and ˇ-L-Arap residues; they are partially substituted with pyruvic acid ketals.
Red algal cell walls contain (1 ! 3), (1 ! 4) –
mixed linkage ˛, ˇ-D(L)-galactans. Most of these
polysaccharides are nonbranched. Their backbone is
made of disaccharide repeating fragments of alternating (1 ! 3)-ˇ- and (1 ! 4)-˛-linked Galp. The former
units (G) always have D-configuration, whereas the
latter ones (D or L) are present as the D- (the carrageenan family) or L- (the agaran family) enantiomers
(Fig. 22.2b,c). Sulfate hemiesters, methyl ethers, and
pyruvic acid are commonly bound to these polysaccharides. Sulfate and/or occasionally methyl groups may
occur at the O-2 and/or O-4 position(s) of the (1 !
3)-ˇ-linked Galp units and at O-2, O-3-, and/or O-6
position(s) of the (1 ! 4)-˛-linked Galp units; pyruvic
acid may be attached to (1 ! 3)-ˇ-D-Galp residues as
ketals at O-4 and O-6 positions [22.81, 82]. The 3,6anhydro derivatives of D(L) units may be present in the
backbone of carrageenose (agarose) after elimination
of sulfate from O-6 by enzymatic or alkali treatment.
Agarose, a simplified structure of agar, is a sequence of
548 Part D Marine Algal Biotechnology
Table 22.2 (continued)
Order
Species
M/G value
References
Laminariales
Laminaria pallida
2.33 (stipes)
[22.48]
Laminaria digitata
1.45
[22.11]
1:352:08 (blade)
[22.29]
Laminaria longicruris
1:442:17
Agarum cribosum
1.30 (blade)
Macrocystis pyriphera
1:381:70
[22.7, 11, 29, 32, 49]
1.52 (frond)
1.02 (stipes)
1.41 (blade)
Macrocystis boryana
0.79
[22.11]
Lessonia trabeculata
1.73
[22.50]
Lessonia variegata
1.95
[22.26]
Ecklonia radiata
1.60
Scytosiphonales
Scytosiphon lomentaria
1.15; 0.67
the high-M and low-M alginates consist mainly of
homopolymeric blocks (GG, MM), which are almost
directly connected and contain few or no heteropolymeric blocks. It was also found that young algal tissues
are rich in M-blocks, and that the difference between
the alginates from different species was mainly due to
the contribution of the older parts of thalli [22.11].
22.2.2 Sulfated Galactans
Sulfated galactans are common cell wall matrix
polysaccharides of green (Clorophyta) and red (Rhodophyta) algae. They are polymers of partially sulfated
ˇ-D- sand/or ˛-D(L)-galactopyranosyl (Galp) units.
Sulfated galactans from cell walls of green algae (genera Codium and Bryopsis) were reported to
be both homo and heteropolysaccharides, depending on the species [22.17, 19, 20, 22, 51]. Polysaccharides isolated from Codium isthmocladum [22.20] and
Codium yezoense [22.17, 52] are sulfated homogalactans containing similar backbones, composed mainly
of (1 ! 3)-linked ˇ-D-Galp units and short oligosaccharide side chains bound at O-6. The units were
sulfated mainly at O-4 and rarely at O-6, and nonreducing terminal residues were pyruvylated forming
cyclic 3,4-ketals. Sulfated galactan isolated from Bryopsis plumosa (Bryopsidales, Chlorophyta) consist of
a (1 ! 3)-linked ˇ-D-Galp partially sulfated on O6 and substituted with pyruvic acid, forming 4,6-ketals [22.19]. A branched sulfated (1 ! 3), (1 ! 6)ˇ-D-galactan was isolated from Codium fragile. This
polysaccharide has a (1 ! 3)-linked partially 4-O-sulfated ˇ-D-Galp backbone with some 3,4-pyruvated ˇD-Galp stubs at O-6 positions [22.21]. By contrast,
galactans isolated from Codium fragile [22.51] and
Codium cylindricum [22.22] contain other sugar units –
arabinose and glucose, respectively. Nevertheless, the
!3)-ˇ-D-Galp4S-(1! units still predominate in these
polysaccharides. Water-soluble highly sulfated arabinans, galactans, and/or arabinogalactans were isolated
from Codium fragile and Codium vermilara [22.18].
These polysaccharides are composed of (1 ! 3)-linked
ˇ-D-Galp and ˇ-L-Arap residues; they are partially substituted with pyruvic acid ketals.
Red algal cell walls contain (1 ! 3), (1 ! 4) –
mixed linkage ˛, ˇ-D(L)-galactans. Most of these
polysaccharides are nonbranched. Their backbone is
made of disaccharide repeating fragments of alternating (1 ! 3)-ˇ- and (1 ! 4)-˛-linked Galp. The former
units (G) always have D-configuration, whereas the
latter ones (D or L) are present as the D- (the carrageenan family) or L- (the agaran family) enantiomers
(Fig. 22.2b,c). Sulfate hemiesters, methyl ethers, and
pyruvic acid are commonly bound to these polysaccharides. Sulfate and/or occasionally methyl groups may
occur at the O-2 and/or O-4 position(s) of the (1 !
3)-ˇ-linked Galp units and at O-2, O-3-, and/or O-6
position(s) of the (1 ! 4)-˛-linked Galp units; pyruvic
acid may be attached to (1 ! 3)-ˇ-D-Galp residues as
ketals at O-4 and O-6 positions [22.81, 82]. The 3,6anhydro derivatives of D(L) units may be present in the
backbone of carrageenose (agarose) after elimination
of sulfate from O-6 by enzymatic or alkali treatment.
Agarose, a simplified structure of agar, is a sequence of