多糖的甲基化方法及图谱解析

Method and Analysis of Methylation of Polysaccharides

本文对微量多糖的甲基化方法进行了研究。0.1 mg多糖样品用0.3 mL二甲亚砜溶解后,加入10 mg氢氧化钠粉末,室温下超声20 min。冰浴冷却后加入0.1 mL碘甲烷1,8～20℃下超声20 min,再加入0.1 mL碘甲烷,超声20 min。加入1 mL含4 mmol/L Na2S2O3的水,终止甲基化反应。反应液用0.5 mL氯仿提取4次,氯仿提取液用0.5 mL水处理5次。氯仿相用无水硫酸钠脱水后,氮气吹干。该法简便易行,甲基化程度高,适用于易溶(或难溶)于水和二甲亚砜的多糖。此外,本文对部分甲基化的糖醇乙酰酯衍生物的质谱图解析进行了阐述,并对特殊糖类样品的甲基化方法进行了说明。

Methylation of trace polysaccharide was studied.Polysaccharide sample（0.1 mg） was dissolved in 0.3 mL dimethyl sulfoxide,followed by adding 10 mg powdered NaOH and sonicating for 20 min.After cooling on ice,0.1 mL CH3I was added and sonicated for 20 min at 18-20 ℃.After cooling,CH3I was added again and sonicated for 20 min.Water（1 mL） containing 4 mmol/L Na2S2O3 was added to stop the methylation reaction.The methylated solution was extracted four times with 0.5 mL chloroform,followed by extracted five times with 0.5 mL water.The chloroform fraction was mixed with anhydrous sodium sulfate to remove the residue water and dried with N2.The method was simple and easy.The methylation degree of the product was high for polysaccharides soluble or insoluble in water and DMSO.In addition,the resolution of partially methylated alditol acetate was explained and the methylation methods for special carbohydrates were also illuminated.