Biology Reference
In-Depth Information
roles in various kinds of biological processes [4]. Oligosaccharide-
polypeptide conjugates have been prepared by many researchers
to develop model compounds for molecular recognition [18].
On the basis of these researches, as a new model compound
for biological applications, the preparation of polysaccharide-
polypeptide conjugate, i.e., amylose-grafted poly(
l
-glutamic acid),
by chemoenzymatic method was investigated (Fig. 6.9) [19].
First, maltopentaosylamine was condensed with the pendant
carboxyl groups of poly(
l
-glutamic acid) using a condensing agent
to give a maltopentaose-grafted poly(
l
-glutamic acid). Then, the
phosphorylase-catalyzed polymerization of Glc-1-P from the
maltooligosaccharide primers on the poly(
l
-glutamic acid) main-
chain was performed to produce the amylose-grafted poly(
l
-glutamic
acid). The maltopentaose-grafted poly(
l
-glutamic acid) formed a
helical conformation at lower pH and a random coil conformation
at higher pH. However, little
α
-helix content was observed for the
amylose-grafted poly(
l
-glutamic acid), indicating that the helical
formation was disturbed by the amylose chains, probably owing to
steric hindrance.
OH
OH
O
O
HO
HO
HO
HO
OH
OH
OH
O
OH
O
NH
3
HCO
3
aq
.
OH
OH
O
O
HO
HO
O
O
OH
OH
NH
2
O
O
HO
HO
OH
3
3
OH
OH
Maltopentaose
O
H
N
C
n
HOBt / BOP
HO
O
O
O
OH
N
N
C
C
O
HO
HO
OH
n
OH
O
OH
O
HO
HN
O
HO
O
O
OH
O
HO
3
OH
Glc-1-P
Phosphorylase
O
O
OH
H
N
H
N
C
C
O
HO
HO
OH
n
OH
O
OH
O
HO
HN
O
HO
O
O
OH
O
HO
m
OH
Chemoenzymatic synthesis of amylose-grafted poly(l
-
glutamic
acid) by means of phosphorylase-catalyzed enzymatic
polymerization.
Figure 6.9
