Enzymatic synthesis of an α-chitin-like substance via lysozyme-mediated transglycosylation

The enzymatic synthesis of an α-chitin-like substance via a non-biosynthetic pathway has been achieved by transglycosylation in an aqueous system of the corresponding substrate, tri-N-acetylchitotriose [(GlcNAc)3] for lysozyme. A significant amount of water-insoluble product precipitated out from the reaction system. MALDI-TOFMS analysis showed that the resulting precipitate had a degree of polymerization (DP) of up to 15 from (GlcNAc)3. Solid-state 13C NMR analysis revealed that the resulting water-insoluble product is a chitin-like substance consisting of N-acetylglucosamine (GlcNAc) residues joined exclusively in a β-(1→4)-linked chain with stringent regio-/stereoselection. X-ray diffraction (XRD) measurement as well as 13C NMR analysis showed that the crystal structure of synthetic product corresponds to α-chitin with a high degree of crystallinity. We propose that the multiple oligomers form an α-chitin-like substance as a result of self-assembly via oligomer–oligomer interaction when they precipitate.

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