苹果果胶活性寡聚半乳糖醛酸的分离制备及其ESI-MS分析研究

Studies on Preparation of Oligogalacturonic Acids from Apple Pectin and Analysis by ESI-MS

苹果果胶多糖经脱酯化得到果胶酸,以果胶酸为底物通过酶解得到聚合度为2～8的果胶寡糖混合物,并运用阴离子交换柱层析对果胶寡糖混合物进行了分离制备.结果表明,以果胶酸为底物在40℃酶解反应1h为最佳酶解条件得到果胶寡糖混合物,经分离制备得到聚合度为2～5的寡聚半乳糖醛酸单体,总得率为37%,TLC和ESI-MS检测其纯度为92%以上.运用ESI-MS分析寡聚半乳糖醛酸时发现除单体的分子离子峰外,还存在二聚体的分子离子峰,并对二聚体的存在进行了确认。

A low degree of esterification pectic acid was obtained by sodium hydroxide treatment of apple pectin.Pectic acid was depolymerized with a commercially available pectinase and a mixture of oligo-GalA（DP2-8） was pooled together,the mixture was separated by a low-pressure anion-exchange resin column chromatography to obtain pure oligo-GalA.The degradation conditions were optimized as enzymatic reaction at 40 ℃ for 1 h,oligo-GalA monomers in the range of 2～5 with a purity degree over 92% analyzed by TLC and ESI-MS were prepared（yield of 37%）.The results indicated that there also existed dimer molecular ion peaks along with oligogalacturonic acid monomer molecular ion peaks,and the presence of the dimer were identified by ESI-MS/MS.