Phosphorylase catalyzes enzymatic polymerization of a-D-glucose 1-phosphate (Glc-1-P) as a monomer using a maltooligosaccharide primer to produce α(1→4)-glucan (amylose). Because of loose specifiity for the recognition of substrates, phosphorylase recognizes several analogue substrates of Glc-1-P to give non-natural oligosaccharides. In this study, the synthesis of 2-deoxyamyloses was investigated by thermostable phosphorylase (from Aquifex aeolicus VF 5)-catalyzed enzymatic polymerization of D-glucal via the in-situ production of α-2-deoxy-D-glucose 1-phosphate (2dGlc-1-P). The enzymatic copolymerization of D-glucal with Glc-1-P was also carried out. The 1H NMR spectrum of the isolated product by the enzymatic polymerization of D-glucal supported the structure of 2-deoxyamylose. The XRD profile of the product showed a different pattern from that of amylose, suggesting its intrinsic crystalline structure. Furthermore, the 1H NMR spectra of the products, which were obtained by the enzymatic copolymerization of D-glucal and Glc-1-P, indicated that the compositional ratios of the two units were almost depending on the feed ratios, suggesting comparable reactivities of D-glucal and Glc-1-P. The XRD measurement of the products with the comparable unit ratios showed a broad diffraction pattern compared with those of amylose and 2-deoxyamylose. It suggested that the products had amorphous structure owing to random sequence of 2-deoxyglucose units and glucose units. In addition, the product with 4: 6 unit ratio could form a film by casting the DMSO solution and drying.

Synthesis of 2-deoxyamyloses by phosphorylase-catalyzed enzymatic polymerization

2019 Fall National Meeting

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