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

The enzymatic synthesis of an alpha-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 C-13 NMR analysis revealed that the resulting water-insoluble product is a chitin-like substance consisting of N-acetylglucosamine (GlcNAc) residues joined exclusively in a beta-(1 -> 4)-linked chain with stringent regio-/stereoselection. X-ray diffraction (XRD) measurement as well as C-13 NMR analysis showed that the crystal structure of synthetic product corresponds to alpha-chitin with a high degree of crystallinity. We propose that the multiple oligomers form an alpha-chitin-like substance as a result of self-assembly via oligomer-oligomer interaction when they precipitate. (C) 2011 Elsevier Ltd. All rights reserved.