Chemoenzyamtic synthesis and self-assembling gelation behavior of amylose-grafted poly(γ-glutamic acid)

Publication date: April 2017
Source:International Journal of Biological Macromolecules, Volume 97
Author(s): Takuya Shouji, Kazuya Yamamoto, Jun-ichi Kadokawa
In this study, we investigated chmemoenzymatic synthesis of amylose-grafted poly(γ-glutamic acid) (PGA) as a new artificial saccharide-peptide conjugate composed of two biological macromolecules. Maltooligosaccharide as a primer of enzymatic polymerization by phosphorylase catalysis was first introduced on the PGA main chain by the condensation reaction using the condensing agent in NaOH aq. Thermostable phosphorylase-catalyzed enzymatic polymerization of α-d-glucose 1-phosphate (G-1-P) as a monomer was then performed from the primer chain ends of the product to obtain amylose-grafted PGAs, which formed hydrogels in reaction media depending on the G-1-P/primer feed ratios. The powder X-ray diffraction patterns of lyophilized samples (cryogels) from the hydrogels suggested that the amylose graft chains formed double helixes, which acted as cross-inking points for self-assembling hydrogelation. The scanning electron microscopic images of the cryogels showed regularly controlled porous morphologies. Moreover, pore sizes of the cryogels increased with increasing the G-1-P/primer feed ratios, whereas the degrees of substitution of primer on the PGA main chain did not obviously affect pore sizes.



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