【摘要】 对当归多糖ASP3的糖链结构进行分析.分别采用0.2mol/L三氟乙酸(Trifluoroacetic acid,TFA)和内切-α-(1→4)-聚半乳糖醛酸酶(EndoPG)对ASP3进行部分酸水解和酶水解,并对水解前后多糖组分的1D和2D NMR光谱特征进行分析.实验结果表明,ASP3是一种果胶多糖.GalpA和Rhap位于多糖分子的主链,由1→4-D-GalpA相连形成的"光滑区"(半乳糖醛酸聚糖)是其主要组成部分;由α-(1→4)-GalpA通过O4位与α-(1→2)-和α-(1→2,4)-Rhap的O2位交替连接所形成的重复单元[→4)-α-GalpA-(1→2)-α-Rhap-(1→]构成具有较高分支的"毛发区"(富含中性糖侧链的鼠李半乳糖醛酸聚糖).Galp和Araf是中性糖侧链的主要组成,通过Rhap残基的O4位与主链相连.非还原性末端T-β-Galp,β-(1→3)-,β-(1→3,6)-,β-(1→4)-,β-(1→4,6)-Galp聚合形成以β-(1→3,6)-Galp为分支点的β-(1→6)-半乳聚糖和以β-(1→4,6)-Galp为分支点的β-(1→4)-半乳聚糖.T-α-Araf,α-(1→5)-Araf和α-(1→3,5)-Araf聚合形成以α-(1→3,5)-Araf为分支点的α-(1→5)-阿拉伯聚糖.此外,由α-(1→5)-阿拉伯聚糖通过α-(1→3)连接与β-(1→6)-半乳聚糖末端聚合形成阿拉伯半乳聚糖.更多还原

【Abstract】 The structural features of polysaccharide ASP3 were studied.ASP3 was hydrolyzed with 0.2 mol/L trifluoroacetic acid and was enzymic hydrolyzed with endo-α-(1→ 4)-polygalacturonases.NMR analysis method was conducted on the samples.The results indicated that ASP3 was a kind of pectic polysaccharide which contained the main part of homogalacturonan fragments as "smooth regions" with α-(1→ 4)-GalpA,and rhamnogalacturonan segments as "hairy regions" backbone.Gal and Ara,which were the mainly constitution of the branch,substituted at O4 position of Rhap residues in the backbone.Man and Glc were linked as arabinogalactan,galactan and arabinan.Terminal,β-(1→ 3)-,β-(1→ 3,6)-,β-(1→ 4)-,and β-(1→ 4,6)-Galp as well as residues of terminal,α-(1→ 5)-,and α-(1→ 3,5)-Araf were linked to form β-(1→ 6)-or β-(1→ 4)-galactans bearing 3,6-or 4,6-substituted β-Galp residues as branched points respectively,and short α-(1→ 5)-arabinan possessing 3,5-substituted α-Ara residues as branched points.In addition,arabinogalactan was found to contain branched sugar chains of α-(1→ 5)-arabinan attached to the linear chains of β-(1→ 6)-galactan by 1,3-linkages.更多还原