18C型肺炎球菌荚膜多糖的水解及水解片段的特性

目的探索不同乙酸水解条件对18C型肺炎球菌多糖的水解效果。方法选择60℃和92℃2种温度,以不同乙酸浓度和不同时间对多糖进行水解,用层析法检测相对分子质量,免疫双扩散法和ELISA抑制法分别检测活性。结果0.2mol/L乙酸92℃水解16h,水解程度趋于稳定,相对分子质量可达57000;1.0mol/L乙酸60℃水解40h,水解程度趋于稳定,相对分子质量可达235000;用1.0mol/L乙酸在不同温度下水解时,随着温度升高,水解程度增加,而在92℃不同乙酸浓度对水解程度几乎无影响。上述条件所得水解片段均保留了抗原性,但随着相对分子质量的降低,抗原性有所减弱。结论在不同条件下,乙酸能将18C型肺炎球菌荚膜多糖水解为不同大小的片段,且未破坏抗原决定簇的基本结构。

Hydrolysis of Pneumococcal Capsular Polysaccharide Type 18C and Characteris tics of Hydrolytic Fragments

Objective To explore the hydrolysis of pneumococcal capsular polysaccharide type 18C with acetic acid under various conditions.Methods Pneumococcal capsular polysaccharide type 18C was hydrolyzed with acetic acid at different concentrations and temperatures for different hours.Determine the relative molecular masses of hydrolytic fragments by chromatography,and the activity by double immunodiffusion test and inhibition ELISA.Results After pneumococcal capsular polysaccharide type 18C was hydrolyzed with 0.2 mol/L acetic acid at 92℃ for 16 h,the hydrolysis degree showed a stable tendency,and the relative molecular mass of hydrolytic fragment was 57 000.However,after the polysaccharide was hydrolyzed with 1.0 mol/L acetic acid at 60℃ for 40 h,the hydrolysis degree also showed a stable tendency,while the relative molecular mass of hydrolytic fragment was 235 000.When the polysaccharide was hydrolyzed with 1.0 mol/L acetic acid,the hydrolysis degree increased with the increasing temperature.However,at 92℃,the concentration of acetic acid showed little influence on hydrolysis degree.All the hydrolytic fragments under above-mentioned conditions remained antigenicities.Along with the decreasing relative molecular mass,the antigenicity of hydrolytic fragment decreased.ConclusionPneumococcal capsular polysaccharide type 18C was hydrolyzed into fragments of different sizes with acetic acid under different conditions.However,the structure of antigenic determinants was not damaged.