Biology Reference
In-Depth Information
OH
OH
O
O
O
trehalose
phosphorylase
(EC 2.4.1.64)
HO
HO
OPO
+
HO
HO
OH
OH
OH
O
OH
O
glucose
β
-Glc-1-P
HO
HO
HO
inorganic
phosphate
O
+
OH
OH
O
OH
OH
HO
OH
trehalose
phosphorylase
(EC 2.4.1.231)
O
O
HO
HO
trehalose
+
HO
HO
O
OH
OH
OH
OPO
glucose
O
Glc-1-P
Figure 3.8
Catalyses of trehalose phosphorylases.
trehalose where maltose phosphorylase and the inversion type
trehalose phosphorylase act on maltose in the presence of inorganic
phosphate [22]. In principle, it should also be possible to use sucrose
phosphorylase and the retaining type trehalose phosphorylase
acting on sucrose in the presence of inorganic phosphate.
Kojibiose phosphorylase was found in the cell-free extract of a
thermophilic bacterium accompanied with trehalose phosphorylase
[23]. This enzyme catalyzes the reversible phosphorolysis of
kojibiose into
-Glc-1-P and glucose. The reverse reaction by
kojibiose phosphorylase catalysis was utilized for the synthesis of
kojioligosaccharides (Fig. 3.9) [24]. When the mixtures of various
proportions of glucose and
β
-Glc-1-P were allowed to react in the
presence of kojibiose phosphorylase, kojioligosaccharides were
produced. The average DPs of the products increased with the
decreasing proportions of glucose.
β
Three
enzymes
catalyze
the
phosphorolysis
of
β
-(1
→
3)-
linked glucans:
β
-1,3-oligoglucan phosphorylase (EC 2.4.1.30),
laminaribiose
phosphorylase
(EC
2.4.1.31),
and
laminarin
OH
O
O
kojibiose
phosphoryla
se
HO
OH
OH
HO
O
O
O
P
O
+
OH
O
HO
n
HO
HO
OH
HO
O
OH
kojioligosaccharides
glucose
β
-Glc-1-P
+
inorganic phosphate
Figure 3.9
Kojibiose
phosphorylase-catalyzed
synthesis
of
kojioligosaccharides.
