Biology Reference
In-Depth Information
8.2
Preparation of Inclusion Complexes
Composed of Amylose and Strongly
Hydrophobic Polyesters in Parallel
Enzymatic Polymerization System
In the vine-twining polymerization as described in Chapter 7,
the hydrophobicity of the guest polymers is a very important
factor because the driving force for the formation of the inclusion
complexes is probably hydrophobic interaction. However, in
addition to no formation of the inclusion complex from hydrophilic
polymer, e.g., PEG, the preparation of the inclusion complexes had
not been achieved from the polymers with strong hydrophobicity,
e.g., poly(oxepane), attributed to their aggregation in the aqueous
buffer of the solvent for the enzymatic polymerization.
To obtain the inclusion complex from a strongly hydrophobic
guest polymer, a parallel enzymatic polymerization system was
investigated, i.e., two enzymatic polymerizations, which were the
phosphorylase-catalyzed polymerization of
,
giving rise to amylose, and the lipase-catalyzed polycondensation of
dicarboxylic acids and diols, leading to the aliphatic polyesters [7,8],
were simultaneously performed (Fig. 8.8) [9]. As the monomers
for the guest polyesters, the dicarboxylic acid and the diol having
methylene units of 8, hereafter denoted as Diacid-8 and Diol-8,
were firstly employed. The isolated product was characterized by
means of the
Glc-1-P
from
Glc
7
1
H NMR and XRD measurements, which supported the
structures of amylose-polyester inclusion complex.
To demonstrate that the inclusion complex composed of amylose
and the strongly hydrophobic polyester could be prepared by only
the present parallel enzymatic polymerization system, following two
experiments were performed. First, amylose-forming polymerization
was performed in the presence of the polyester having methylene
units of 8. In
1
H NMR spectrum of the product, the signals due to
only amylose were observed, indicating that this polymerization
method did not afford corresponding inclusion complex. However,
polyester-forming polycondensation was carried out in the presence
of amylose. Consequently, although the monomers for the polyester
were included in the cavity of amylose, the polyester was not
included in it, confirmed by means of
1
H NMR measurement. These
results indicated that the inclusion complex composed of amylose
and the strongly hydrophobic polyester was prepared by only the
present parallel enzymatic polymerization system.
