不同分子质量及结构特征果胶片段的制备及分离

The preparation of pectin fragment with different molecular weight and structure and its separation

以商业果胶为原料依次采用酸水解、膜分离、酶水解和离子交换色谱分离方法制备具有不同分子质量及结构特征的果胶片段。将果胶一次或分次加入1.5 mol/L HCl溶液中,配制成240 g/L的溶液,于80℃下水解6 h,可分别得到分子质量250 k^270 k Da的均一半乳糖醛酸区(homogalacturonan region,HG区)大片段和分子质量约为30 k Da的鼠李半乳糖醛酸聚糖区(rhamnogalacturonan region,RG区)小片段,同时酸水解产物酯化度从原料的61%降为10%;水解液中和后用10 k Da超滤膜脱盐,之后用商业果胶酶Pectinex Ultra SP-L酶解,获得分子质量约70 k Da的果胶多糖片段,所得酶解液再经过DEAE Sepharose Fast Flow弱阴离子交换柱,依次以纯水、0.05~1.0 mol/L Na Cl溶液洗脱,得到果胶片段样品MCP-1,MCP-2,MCP-3,MCP-4,相应的峰位分子质量分别为12.39 k Da,125.33 k Da,146.49 k Da和193.31 k Da,单糖组成分析结果显示样品中半乳糖醛酸含量依次上升,即MCP-1中RG区含量最高,而MCP-4中HG区含量最高。

In this paper, the commercial pectin was used as raw materials to prepare pectin with different molec- ular weight and structure characteristics through acid hydrolysis, membrane separation, enzyme digestion and ion ex- change chromatography. Pectin with an initial concentration of 24% （w/v） was prepared in 1.5 mol/L HC1 and hy- drolyzed at 80 ~C for 6h to produce big HG fragments and small RG fragments. Meanwhile, the DM of hydrolysates was reduced from 61% to 10%. Salts were dislodged by uhrafihration（MWCO = 10 kDa） and the pectin was further degraded to small ones of about 70 kDa by pectinase, The DEAE chromatographic column was used for further separa- tion, elution with pure water and 0.05 - 1.0 mol/L NaC1 in turn. MCP-1, MCP-2, MCP-3, MCP-4 was obtained and their MP were 12.39 kDa, 125.33 kDa, 146.49 kDa and 193.31 kDa, respectively. GalA content indicated that the content was the highest in RG of MCP-1 and HG of MCP-4. Research progress on lipase A from Candida antarctica Abstract： Lipase A from Candida antarctica （CALA） is one of useful biocatalyst with many application that have been described in the fields of food, medicine, cosmetic industry etc. This enzyme has some unique features, such as high thermostability, strong enatioselectivity, and selectivity towards trans-fatty acids, etc. In the present review, the mo- lecular structure, gene （CALA） clone and expression, the properties and applications of CALA were briefly described and discussed to point out some new applications and novel characteristics of this biocatalyst.