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将壳聚糖置于不同盐酸浓度的反应体系中进行降解反应,制备得到不同聚合度的壳寡糖混合物;采用凝胶过滤法分离混合物,旨在获得特定聚合度(DP=5-6)的壳寡糖。实验表明:在不同温度(40℃、60℃、80℃)和不同盐酸浓度(6 mol/L、9 mol/L、11 mol/L)下,壳聚糖均能被有效的降解;不同降解液中各种聚合度壳寡糖组成不一;其中,在9mol/L盐酸和60℃的反应条件下,降解液中壳五糖和壳六糖含量最高,达到16.2%。采用以葡聚糖凝胶Sephadex G-15为介质的层析法,实现了对降解液中壳低聚糖混合物的初步分离,获得主要含壳五糖和壳六糖的组分。该组分经高效液相色谱法鉴定,除预期的壳五糖和壳六糖外,还含有另一未知化合物。通过13C和1H核磁共振分析,并结合专一性壳聚糖酶的酶解实验,对其进行表征和鉴定,结果表明:该化合物为聚合度为7的壳七糖。
The chitosan was placed in a reaction system of different concentration of hydrochloric acid for degradation reaction to prepare chitooligosaccharides mixture with different polymerization degree; the mixture was separated by gel filtration to obtain the specific polymerization degree (DP = 5-6) Chitooligosaccharides. The results showed that chitosan could be effectively degraded under different temperatures (40 ℃, 60 ℃, 80 ℃) and different concentrations of hydrochloric acid (6 mol / L, 9 mol / L, 11 mol / L) The oligomeric chitooligosaccharides with various degrees of polymerization in liquid have different compositions. Among them, under the reaction conditions of 9 mol / L hydrochloric acid and 60 ℃, the content of chitosan and hexasaccharide in chitosan was the highest, reaching 16.2%. A chromatographic method using sephadex G-15 as a medium was used to obtain a preliminary separation of the chitooligosaccharide mixture in the degradation solution and to obtain the major chitooligosaccharides and the hexasaccharide components. This component was identified by high performance liquid chromatography and contained an unknown compound in addition to the expected chitose and hexasaccharide. The 13C and 1H nuclear magnetic resonance analysis, combined with specificity chitosanase enzymatic hydrolysis experiments, its characterization and identification, the results show that: the compound is a degree of polymerization of 7 heptasaccharide.