目的 研究普通念珠藻多糖分离纯化方法，并测定其相对分子质量。方法 采用水提醇沉法制备粗多糖，Molish反应和硫酸苯酚法对其进行定性和定量检测，二乙胺基乙基纤维素离子交换柱色谱法进行分离纯化，高效凝胶渗透色谱法测定其相对分子质量。结果 普通念珠藻粗多糖的提取率为8.6%，分离获得一个组成均一的酸性多糖组分NSP，其重均相对分子质量为402 717。结论 NSP为首次从普通念珠藻中分离得到一个酸性多糖组分。

Objective To separate and purify Nostoc commune polysaccharides, and determine their molecular weight. Methods Nostoc commune polysaccharides were obtained by water extraction and alcohol precipitation. After the qualitative and quantitative tests of these crude products by Molish reaction and phenol sulfuric acid method, diethylaminoethyl cellulose (DEAE) ion exchange column chromatography was utilized for their separation and purification. And their molecular weights were determined by high performance gel filtration chromatography (HPGFC). Results The extraction rate of Nostoc commune polysaccharides was 8.6%. After the separation and purification, one homogeneous fraction of NSP was obtained, which was identified as acidic polysaccharides and its average molecular weight was determined to be 402 717. Conclusion NSP is separated from N. commune as acidic polysaccharides for the first time.