Preparation of Amylose-Oligo[(R)-3-hydroxybutyrate] Inclusion Complex by Vine-Twining Polymerization

Abstract

In this study, we attempted to prepare an amylose-oligo[(R)-3-hydroxybutyrate] (ORHB) inclusion complex using a vine-twining polymerization approach. Our previous studies indicated that glucan phosphorylase (GP)-catalyzed enzymatic polymerization in the presence of appropriate hydrophobic guest polymers produces the corresponding amylose–polymer inclusion complexes, a process named vine-twining polymerization. When vine-twining polymerization was conducted in the presence of ORHB under general enzymatic polymerization conditions (45 °C), the enzymatically produced amylose did not undergo complexation with ORHB. However, using a maltotriose primer in the same polymerization system at 70 °C for 48 h to obtain water-soluble amylose, called single amylose, followed by cooling the system over 7 h to 45 °C, successfully induced the formation of the inclusion complex. Furthermore, enzymatic polymerization initiated from a longer primer under the same conditions induced the partial formation of the inclusion complex. The structures of the different products were analyzed by X-ray diffraction, 1H-NMR, and IR measurements. The mechanism of formation of the inclusion complexes discussed in the study is proposed based on the additional experimental results.

Bottom‐Up Synthesized Glucan Materials: Opportunities from Applied Biocatalysis

“…[29a,c] Noncovalent interactions between amylose and guest polymers may contribute to the formation of highly ordered supramolecular structures. [181] Oligomers such as oligo[(R)-3-hydroxybutyrate] [182] and polymers such as PTHF, [183] poly(𝛿-valerolactone), [184] poly(trimethylene carbonate), [185] poly(𝛽-propiolactone), [186] and poly(𝛾-butyrolactone) [187] are utilized for inclusion complex formation via vine-twining polymerization. The hydrophobicity, molecular weight, and chirality of guest polymers significantly influence complexation with amylose.…”

Fabrication of Nanostructured Supramolecules through Helical Inclusion of Amylose toward Hydrophobic Polyester Guests, Biomimetically through Vine-Twining Polymerization Process

“…Vine-twining polymerization was investigated using the structural isomer of PBL, which has substituents (methyl groups), that is, poly[(R)-3-hydroxybutyrate] (PRHB), as a guest polyester. As a result, only its oligomer with low molecular weight (approximately 500) gave rise to an amylosic inclusion complex under specific conditions in the GPcatalyzed enzymatic polymerization field as follows [41]. The enzymatic polymerization using oligo[(R)-3-hydroxybutyrate] (ORHB) is first examined at 70 • C, higher than that for the general vine-twining polymerization (at 45-50 • C), catalyzed by thermostable GP (from Aquifex aeolicus VF5), which shows stability at such a higher temperature.…”

“…The fabrication of macroscopic structures from amylose-grafted Pg-GA networks was attempted [53]. Because the enzymatic polymerization using thermostable GP (from Aquifex aeolicus VF5) at elevated temperatures has been found to produce a water-soluble amylosic product with a single chain (called single amylose) in an equilibrium state between polymerization and phosphorolysis (chain elongation and cleavage reactions, respectively), the enzymatic polymerization from the primer-modified Pg-GA was first conducted with or without PLLA at 80 • C for single-amylose-chain production [41]. Double-helix formation was then performed by cooling the reaction mixture at room temperature.…”

Vine-Twining Inclusion Behavior of Amylose towards Hydrophobic Polyester, Poly(β-propiolactone), in Glucan Phosphorylase-Catalyzed Enzymatic Polymerization

“…For example, slender polyesters with moderate hydrophobicity, e.g., poly(ε-caprolactone), poly(δ-valerolactone), and poly(γ-butyrolactone) (PCL, PVL, and PBL), that do not carry side substituents, can be employed as the polymeric guests to construct the corresponding amylosic helical inclusion complexes through vine-twining polymerization [ 23 , 24 , 25 ]. When vine-twining polymerization was attempted in the presence of the structural isomer of PBL with methyl substituents, i.e., poly[( R )-3-hydroxybutyrate] (PRHB), as the guest polyester, only its low molecular weight (approximately 500) oligomer showed ability for the formation of an inclusion complex with amylose under the following specific conditions in the GP-catalyzed enzymatic polymerization system [ 26 ]. The enzymatic polymerization using oligo[( R )-3-hydroxybutyrate] (ORHB) was first caried out by the thermostable GP (from Aquifex aeolicus VF5) catalysis at elevated temperature (at 70 °C), higher than that for the general vine-twining polymerization (at 45–50 °C), to obtain water-soluble short α(1→4)-glucan (amylosic oligomer, named single amylose without double helical assembly) [ 27 ], that interacts weakly with ORHB.…”