目的  研究采用过氧化氢法和高压均质法降解对6A型肺炎球菌多糖（type 6A pneumococcal polysaccharide，PnPS6A）结构和抗原性的影响。方法  分别采用过氧化氢法〔将过氧化氢加入多糖（polysaccharide，PS）溶液中，50 ℃反应3 h〕和高压均质法（用高压均质机在5×107 Pa压力下处理PS溶液）降解PnPS6A，降解物经超滤浓缩和冻干后，获得降解的PnPS6A。分别用核磁共振氢谱（nuclear magnetic resonance hydrogen spectrum，¹H-NMR）和双向免疫扩散法检测PnPS6A降解物的结构和抗原性，用抑制ELISA检测降解和未降解的PnPS6A的抗原一致性。结果  2种降解方法均能降低PnPS6A的相对分子质量。2种降解的PnPS6A对PnPS6A抗血清抑制的半数有效浓度与未处理的PnPS6A为同一个数量级，表明降解的PnPS6A的抗原性没有改变。¹H-NMR分析显示，2种降解的PnPS6A的结构与未处理的PnPS6A一致。结论  2种降解方法都能降低PnPS6A的相对分子质量，而且对PnPS6A的结构和抗原性不会产生影响。

Objective  To study the effect of degradation with hydrogen peroxide method and high pressure homogenization method on structure and antigenicity of type 6A pneumococcal polysaccharide (PnPS6A) . Methods  PnPS6As were degraded by hydrogen peroxide method [adding hydrogen peroxide into polysaccharide (PS) solution and reacting at 50 °C for 3 h] or high pressure homogenization method (degrading with high pressure homogenizer at 5×10⁷ Pa ). After the degraded products were treated by ultrafiltration concentration and freeze-drying, the degraded PnPS6As were obtained. The structure and antigenicity of PnPS6A were detected with nuclear magnetic resonance hydrogen spectrum (¹H-NMR）and double immunodiffusion test, respectively. The antigenicity consistency of treated and untreated PnPS6A was analyzed by inhibition ELISA. Results  Both degradation methods could reduce the relative molecular weight of PnPS6A. The half effective concentrations?for antisera inhibition of 2 degraded PnPS6As were in the same order of magnitude as the untreated PnPS6A, indicating no antigenicity change in degraded PnPS6A. 1H-NMR analysis showed that the structures of 2 degraded PnPS6A were consistent with that of untreaded PnPS6A. Conclusion  Both degradation methods can reduce the relative molecular weight of PnPS6A, and don’t affect PnPS6A structure and antigenicity.