甘露聚糖肽的结构鉴定

摘要

DEAE-52 cellulose column and Sephacryl S-300 gel column were used to isolate and purify man-natide to give four homogeneous glycopeptides termed as MT1-A, MT1-B, MT2-A and MT2-B. The chemical structure of MT1-A, MT1-B and MT2-B were elucidated using monosaccharide composition analysis, methyla-tion analysis, 1 H-nuclear magnetic resonance( 1 H NMR) spectroscopy, infrared( IR) spectroscopy and amino acids analysis. It was concluded that the monosaccharide composition and connection type of sugar residues of MT1-A, MT1-B and MT2-A were the same as MT2-A reported before while the molecular weight and amino acid content of four homogeneous glycopeptides were slightly different. The 1 H NMR spectrum of MT2-A was regarded as the standard reference spectrum and the anomeric region of each spectrum (δ 4. 89—5. 90 ) was selected as the identification region. The 1 H NMR spectra of MT1-A, MT1-B, MT2-A and different batches of mannatide were compared with the standard reference spectrum, using the correlation coefficient to quantita-tively calculate the similarity. The results showed that mannatide was a mixture of several kinds of homoge-neous glycopeptides with the same glycan structure but different molecular weight and amino acid content.%采用离子交换柱层析和凝胶柱层析从甘露聚糖肽原料中分离纯化得到4种均一糖肽MT1-A, MT1-B, MT2-A和MT2-B；通过单糖组成分析、甲基化分析、氢核磁共振谱(1H NMR)、红外光谱(IR)和氨基酸组成分析等手段对均一糖肽MT1-A, MT1-B和MT2-B的结构进行了鉴定。结果表明,3种均一糖肽的单糖组成、糖残基的连接方式与MT2-A相同,但是分子量以及氨基酸总量有所不同。测定了不同批次甘露聚糖肽原料的1 H NMR谱,以MT2-A的1 H NMR谱图为标准谱,以异头氢区域为鉴定区域,通过计算不同批次甘露聚糖肽原料以及其它3种均一糖肽与MT2-A的1 H NMR谱的相关系数,定量评价了不同批次甘露聚糖肽原料与4种均一糖肽的相似程度。结果表明,甘露聚糖肽是由糖链结构一致、分子量和氨基酸含量不同的几种均一糖肽构成的混合物。