Abstract
In this review article, the precise synthesis of functional polysaccharide materials using phosphorylase-catalyzed enzymatic reactions is presented. This particular enzymatic approach has been identified as a powerful tool in preparing well-defined polysaccharide materials. Phosphorylase is an enzyme that has been employed in the synthesis of pure amylose with a precisely controlled structure. Similarly, using a phosphorylase-catalyzed enzymatic polymerization, the chemoenzymatic synthesis of amylose-grafted heteropolysaccharides containing different main-chain polysaccharide structures (e.g., chitin/chitosan, cellulose, alginate, xanthan gum, and carboxymethyl cellulose) was achieved. Amylose-based block, star, and branched polymeric materials have also been prepared using this enzymatic polymerization. Since phosphorylase shows a loose specificity for the recognition of substrates, different sugar residues have been introduced to the non-reducing ends of maltooligosaccharides by phosphorylase-catalyzed glycosylations using analog substrates such as α-d-glucuronic acid and α-d-glucosamine 1-phosphates. By means of such reactions, an amphoteric glycogen and its corresponding hydrogel were successfully prepared. Thermostable phosphorylase was able to tolerate a greater variance in the substrate structures with respect to recognition than potato phosphorylase, and as a result, the enzymatic polymerization of α-d-glucosamine 1-phosphate to produce a chitosan stereoisomer was carried out using this enzyme catalyst, which was then subsequently converted to the chitin stereoisomer by N-acetylation. Amylose supramolecular inclusion complexes with polymeric guests were obtained when the phosphorylase-catalyzed enzymatic polymerization was conducted in the presence of the guest polymers. Since the structure of this polymeric system is similar to the way that a plant vine twines around a rod, this polymerization system has been named “vine-twining polymerization”. Through this approach, amylose supramolecular network materials were fabricated using designed graft copolymers. Furthermore, supramolecular inclusion polymers were formed by vine-twining polymerization using primer–guest conjugates.
Highlights
Polysaccharides are commonly present in nature and have been identified as vital materials for important in vivo functions [1]
glucose 1-phoshate (Glc-1-P) glucosylations with respect tointhe acceptor is present in the system, the of successive themaltooligosaccharide presence of phosphorylase occur present in the reaction system, the to successive the presence of phosphorylase as a propagation of polymerization yield the glucosylations α(1 4)-glucan in polymer, i.e., amylose (Figure 3b) occur as a propagation of polymerization to yield the α(1Ñ4)-glucan polymer, i.e., amylose
When the phosphorylase-catalyzed enzymatic polymerization of Glc-1-P with glycogen was carried out in aqueous acetate buffer solution, followed by the standing of the reaction mixture under ambient atmosphere for 24 h, the solution was fully converted into a hydrogel (Figure 7)
Summary
Polysaccharides are commonly present in nature and have been identified as vital materials for important in vivo functions [1] These molecules are composed of monosaccharide residues linked together through glycosidic bonds, a type of covalent linkage that joins a monosaccharide residue at its anomeric position to another group, typically another saccharide moiety, such that it is structurally a result of dehydrative condensation between the components’ two hydroxy groups (Figure 1) [2,3,4]. Is an enzyme that has been employed synthesize amylose synthesize amylose withPhosphorylase a precise stereoand regio-controlled structure to [16]. This enzymatic approachofprovides pure approach provides pureregio-controlled amylose sample, which[16].
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