牛奶大分子蛋白的水解及其抗原性变化

Allergenicity change of hydrolyzed cow's milk by proteases

目的 :将婴儿乳粉以不同的食品级蛋白酶水解 ,降低牛奶的分子量 ,考察牛奶酶水解产物过敏原性的变化。方法 :采用胃蛋白酶、胰蛋白酶和自制胰酶制品对婴儿奶粉进行酶解 ,以快速蛋白质液相色谱测得酶解产物分子量分布和所占比例。通过实验动物主动、被动皮肤反应和口服致敏肠腔通透性变化观察不同酶水解后牛奶的过敏原性变化。结果 :快速蛋白质液相色谱结果表明蛋白酶水解牛奶后 ,牛奶蛋白分子量明显降低 ,尤以自制胰酶对乳粉的水解程度最高 (分子量 <10 0 0占 92 % ;10 0 0～10 0 0 0占 8% )。胃蛋白酶、胰蛋白酶和胰酶水解产物可以显著抑制由牛奶蛋白引起的小鼠耳速发型主动皮肤过敏 ,抑制率分别为 5 1%、83%和 86 %。小鼠同种及异种被动皮肤过敏反应实验中 ,与未水解奶粉组比较 ,同种皮肤过敏反应三种酶解产物炎性渗出降低率分别为 2 9%、70 %和 82 % ,异种皮肤过敏反应的降低率分别为 34%、70 %和 82 %。口服致敏小鼠肠腔通透性及分泌功能测定结果显示 ,胰酶水解产物致敏小鼠的肠腔伊文思蓝渗出率比未水解前降低了 2 7%。结论 :酶水解后牛奶大分子蛋白物质降解 ,其过敏原性有不同程度的降低 ,尤以胰酶水解产物变化最为显著。

AIM: To evaluate the allergenicity change of hydrolyzed cow's milk by proteases. METHODS: The range of molecular weight of different formulas was determined by fast protein liquid chromatogram (FPLC) after hydrolyzing the infant milk powder with pepsin, trypsin and self-prepare d pancreatin (SPP), and the sensitivity of hydrolysis of formulas milk to protei n antigen was assayed by active, passive cutaneous anaphylaxis in mice and the c hanges of sensitized intestinal permeability in mice were observed. RESU LTS: Molecular weights reduced after the hydrolyzation of milk protein w ith hydrolases and the most effectively degradation reaction was taken by the hy drolyzation with SPP (MW<1 000, 92%; 1 000-10 000, 8%). The vascular permeabilit y induced by the challenge of the milk protein antigen in mice reduced in the ca ses of the hydrolysate of pepsin, trypsin and SPP. The inhibition ratio of immed iate-type cutaneous hypersensitivity reactions were as follows: 51% (pepsin), 8 3% (trypsin) and 86% (SPP), the inhibition ratio of homogeneous passive cutaneou s anaphylaxis were as follows: 29% (pepsin), 70% (trypsin) and 82% (SPP), and th e inhibition ratio of heterogeneous passive cutaneous anaphylaxis were as follow s: 34% (pepsin), 70% (trypsin) and 82% (SPP). Furthermore, hydrolysis of SPP red uced the vascular permeability induced by the small intestine anaphylaxis and th e inhibition ratio was 27%. CONCLUSION: The allergenicity of mil k protein reduces after the hydrolysis with SPP.