Abstract：
Due to the difficulty in obtaining highly branched rhamnogalacturonan-I (RG-I) type pectin, the relationship between the extent of RG-I branching (EB) of pectin and prebiotic/immunomodulatory activity has not been systematically investigated. Moreover, it is only possible to establish a structure-activity relationship using pectin that is highly purified and accurately characterized. In this study, a homogeneous highly branched RG-I type pectin (LBP-P4, a final product) with dual proliferative effects on Bifidobacterium and macrophage was effectively purified for the first time using enzyme hydrolysis combined with ultrafiltration. The RG-I content and EB of LBP-P4 reached 97.32 and 77.12, respectively. Its two branches were composed of arabinan and arabinogalactan-II, containing → 5)-Araf-(1→, →3)-Araf-(1→, →3,6)-Galp-(1→ and →6)-Galp-(1→ residues). The structure-activity relationship analysis indicated that strong prebiotic/immunomodulatory activity of LBP-P4 was depended on its high EB, which was further confirmed by the molecular docking simulation between low/high branched pectin with β-1,6-galactosidase, α-l-arabinanase, and Toll-like receptor 4 (TLR4).
摘要：
由于难以获得高度支化的鼠李糖半乳糖醛酸-I（RG-I）型果胶，尚未系统地研究果胶的RG-I分支（EB）程度与益生元/免疫调节活性之间的关系。此外，只有使用高度纯化和准确表征的果胶才能建立结构-活性关系。在这项研究中,首次使用酶水解结合超滤有效纯化了对双歧杆菌和巨噬细胞具有双重增殖作用的均质高度支化的RG-I型果胶（LBP-P4，终产物）。LBP-P4的RG-I含量和EB分别达到97.32和77.12。它的两个分支由阿拉伯聚糖和阿拉伯半乳聚糖-II组成，包含→5)-Araf-(1→，→3)-阿拉夫-(1→,→3,6)-Galp-(1→和→6)-Galp-(1→残基)。构效关系分析表明,LBP-P4强益生元/免疫调节活性依赖于其高EB,低/高支链果胶与β-1,6-半乳糖苷酶的分子对接模拟进一步证实了这一点,α-1-阿拉伯聚糖酶，和Toll样受体4(TLR4)。
