摘要
目的研究木瓜凝乳蛋白酶(Cp)的单甲氧基聚乙二醇(mPEG)化学修饰对酶活力和抗原性的影响,为该酶的修饰改性提供实验依据。方法在底物保护和无底物保护下,分别以单甲氧基聚乙二醇的两种活化产物mPEG1和mPEG2对木瓜凝乳蛋白酶进行共价修饰,以三硝基苯磺酸法测定各修饰酶的平均氨基修饰度;以大分子酪蛋白和小分子BAEE为底物分别测定各修饰酶的酶活性;以ELISA法检测各修饰酶的抗原性。结果①mPEG1和mPEG2修饰均能降低及消除酶的抗原性,其中mPEG2的效果更为明显。②二者的化学修饰均使酶活力有所下降,其中mPEG1修饰酶的酶活力(分别以酪蛋白和BAEE为作用底物,下同)均高于mPEG2修饰酶的酶活力(尤其是当底物为大分子蛋白质时)。③底物保护下的修饰酶酶活力均显著高于无底物保护的酶活力。结论以mPEG1为修饰剂,在底物保护下的Cp修饰能在消除抗原性的同时,获得仍具较高酶活力的修饰酶。
Objective To study the effect of chemical modification of chymopapain with monomethoxypolyethylene glycol on enzymic activity and antigenicity. Methods Under the substrate protecting and non-substrate protecting, the chymopapain（Cp） was modified with two types of mPEG derivatives mPEG1 and mPEG2 . The average ratio of modified-NH2 was tested by trinitrobenzenesulfonic acid（TNBS） method, the enzymic activity was tested with macromolecular casein and ATEE as substrates, the antigenicity of modified enzyme was determined by ELISA method. Results （ 1 ） Both mPEG1 and mPEG2 can reduce and eliminate antigenicity of Cp, the mPEG2 was better than mPEG1 . （2）The enzymic activities of modified Cp were reduced, the enzymic activities of mPEG1-modified Cp were higher than that of mPEG2-modified Cp （especially macromolecular protein as its substrate）. （3）The enzymic activities in present of ATEE were obviously higher than that in absent of substrate. Conclusion When mPEG1 as the modifier and in present of ATEE, the antigenicity of Cp was completely eliminated, and the enzymic activities were still higher,
出处
《卫生研究》
CAS
CSCD
北大核心
2006年第3期304-307,共4页
Journal of Hygiene Research
基金
广东省重点科研项目(No.C11707)
