Action pattern of Aeromonas hydrophila chitinase on partially N-acetylated chitosan

Oligosaccharides from the digestion of 34% N-acetylated chitosan by Aeromonas hydrophila chitinase were separated by CM-Sephadex C-25 column chromatography. Sugar compositions and the sequences of main oligosaccharides were identified through their N-acetylation, their cleavage with exo-glycosidases, and their degradation with nitrous acid. Hetero-chitooligosaccharides such as GlcN.GlcNAc, GlcN.GlcNAc.GlcNAc, GlcNAc.GlcN.GlcNAc, and GlcNAc.GlcN.GlcNAc.GlcNAc, together with GlcNAc and (GlcNAc)2, were detected. The structure of GlcN.GlcNAc was confirmed by the analysis with proton and carbon NMR spectroscopy. These studies indicate that Aeromonas hydrophila chitinase is more specific toward the N-acetyl-beta-D-glucosaminidic bonds in partially N-acetylated chitosan.