Department of Polymer and Material Science, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China.
Department of Polymer and Material Science, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China; Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Guangdong Provincial Key Laboratory for High Performance Polymer-based Composites, Sun Yat-sen University, Guangzhou 510275, China.
Int J Biol Macromol. 2020 Dec 1;164:1124-1132. doi: 10.1016/j.ijbiomac.2020.07.125. Epub 2020 Jul 16.
An acidic tea polysaccharide (TPSA) isolated from green tea was fractionated using a precipitation-fractionation method into seven fractions with different molecular weights. TPSA was characterized as a hyperbranched polysaccharide with a globular homogeneous conformation by analysis of solution parameters of each fraction using static light scattering and viscosity analyses. Observation by transmission electron microscopy confirmed that TPSA occurred as globular homogeneous particles with size in the range of 20-40 nm. To simulate the branched chain segments of TPSA, four model molecules were designed based on chemical structure of TPSA. Molecular docking analysis indicated that the branched chain segments of TPSA similar to the TPSA-4 model molecule showed preferential binding to α-amylase to form the TPSA/α-amylase complex through hydrogen bonding interactions. Circular dichroism spectroscopy showed that the structure of α-amylase was not significantly affected by TPSA. The mechanism of α-amylase inhibitory activity of TPSA was simulated by molecular docking analysis. The branched chain segments of TPSA similar to the TPSA-4 model molecule likely act as a potential competitor to the starch substrate to inhibit the activity of α-amylase.
从绿茶中分离出的酸性茶多糖（TPSA），采用沉淀分级法，分为 7 个不同分子量的级分。通过静态光散射和粘度分析分析各级分溶液参数，对 TPSA 进行了表征，结果表明 TPSA 是一种超支化多糖，具有球形均相构象。透射电子显微镜观察证实，TPSA 呈球形均相颗粒，粒径在 20-40nm 范围内。为了模拟 TPSA 的支链片段，根据 TPSA 的化学结构设计了四个模型分子。分子对接分析表明，TPSA 的支链片段类似于 TPSA-4 模型分子，通过氢键相互作用优先与α-淀粉酶结合形成 TPSA/α-淀粉酶复合物。圆二色性光谱表明 TPSA 对α-淀粉酶的结构没有显著影响。通过分子对接分析模拟了 TPSA 对α-淀粉酶抑制活性的机制。TPSA 的支链片段类似于 TPSA-4 模型分子，可能作为淀粉底物的潜在竞争性抑制剂，从而抑制α-淀粉酶的活性。
