Analysis of chitin structure by nuclear magnetic resonance spectroscopy and chitinolytic enzyme digestion.

摘要: Solid-state 13C-NMR analysis of chitin prepared from cuticle the tobacco hornworm, Manduca sexta (L.), and crab yielded spectra that demonstrate a high degree chemical homogeneity (greater than 95%) for preparations. The shifts well-resolved carbon signals both samples matched closely those monomeric unit 2-acetamido-2-deoxy-D-glucopyranoside (GlcNAc). Chromatographic products digestion by binary chitinase system (endo splitting exo beta-N-acetylglucosaminidase) isolated M. molting fluid showed major product preparations is GlcNAc. Also detected was minor (product U) had chromatographic retention time on carbohydrate column intermediate between penta- hexasaccharides. Gel filtration chromatography U indicated an apparent molecular weight GlcNAc N,N'-diacetylchitobiose. Cation-exchange after acid hydrolysis revealed presence glucosamine only. Derivatization with trinitrobenzenesulfonate free amino group in U. Solution proton NMR spectroscopy were used to identify as N-monoacetylchitobiose [O-beta-D-2-amino-2-deoxyglucopyranosyl- (1----4)-2-acetamido-2-deoxy-beta-D-glucopyranose] residue at nonreducing end deacetylated. These studies alkali- heat-treated insect or contains trace levels deacetylated residues are released dead-end product, N-monoacetylchitobiose, enzyme system.