中国农业科学 ›› 2015, Vol. 48 ›› Issue (4): 769-777.doi: 10.3864/j.issn.0578-1752.2015.04.14

• 贮藏·保鲜·加工 • 上一篇    下一篇

模拟胃液对Pena 1及其抗原表位免疫原性的影响

赵鑫,高美须,牟慧,沈月,王志东   

  1. 中国农业科学院农产品加工研究所/农业部农产品加工重点实验室,北京 100193
  • 收稿日期:2014-07-07 出版日期:2015-02-16 发布日期:2015-02-16
  • 通讯作者: 高美须,Tel:010-62833881;E-mail:meixugao@263.net
  • 作者简介:赵鑫,E-mail:zhaoxin19900719@163.com
  • 基金资助:
    国家公益性行业(农业)科研专项(201103007)

Effect on Immunogenicity of Pen a 1 and Its Epitopes Digested by Simulated Gastric Fluid

ZHAO Xin, GAO Mei-xu, MOU Hui, SHEN Yue, WANG Zhi-dong   

  1. Institute of Agro-Products Processing Science & Technology, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-Products Processing, Ministry of Agriculture, Beijing 100193
  • Received:2014-07-07 Online:2015-02-16 Published:2015-02-16

摘要: 【目的】Pen a 1是虾中的主要过敏原,已知其5个抗原表位在过敏反应中起着决定性的作用。用全蛋白抗体和表位特异性抗体,检测Pen a 1经体外模拟胃液(simulated gastric fluid,SGF)消化后其抗原表位免疫原性的变化情况,为研究人体消化对Pen a 1的影响机理及脱敏食品的制备提供理论依据。【方法】以刀额新对虾(metapenaeus ensis)为原材料,提取纯化虾过敏原Pen a 1,采用Fmoc化学法合成Pen a 1抗原表位的5个多肽片段(No.1—No.5),分别与载体蛋白KLH和牛血清蛋白BSA偶联制备人工免疫原和包被原。用Pen a 1和制备的多肽免疫原免疫新西兰纯种白兔获得全白蛋抗体和特异性表位抗体。参照美国药典模拟人体胃液的条件消化处理Pen a 1,利用SDS-PAGE和Tricine-SDS-PAGE观察消化后Pen a 1分子量变化;通过免疫印迹(Western-blot)定性观察Pen a 1消化后生成的新蛋白片段与各抗体的结合情况;再经竞争抑制酶联免疫吸附试验(ci-ELISA)定量检测消化后的Pen a 1和表位多肽与各抗体结合能力,从而得出Pen a 1经SGF消化后各抗原表位免疫原性的变化程度。【结果】SDS-PAGE结果显示Pen a 1随SGF消化时间的延长逐渐被降解,在22 kD处生成一些较稳定的新蛋白片段,Tricine-SDS-PAGE结果表明在1.7—18 kD之间无新蛋白片段生成。Western-blot表明消化后分解生成的小分子蛋白与六种抗体发生不同程度结合,其中全蛋白抗体和No.4抗体几乎与生成的所有小分子蛋白结合,在22 kD左右处生成的稳定新蛋白片段均与No.3、4、5抗体有较强的结合,而与No.1、2抗体结合较弱甚至无结合,表明该蛋白携带No.3、4、5表位,而基本无No.1、2表位。ci-ELISA结果显示,Pen a 1经SGF消化后对全蛋白抗体和5个表位抗体的抑制率均显著下降,说明经过消化后Pena1及其抗原表位的免疫原性均明显降低,各抗原表位消化稳定性排序为No.4>No.2>No.1>No.3>No.5,其中No. 2、1、3之间无显著性差异;ci-ELISA检测表位多肽经消化后其免疫原性也显著下降,消化稳定性排序为No.1> No.2 >No.3>No.4>No.5,其中No.2、3、4之间无显著性差异。结合免疫印迹结果可知No.4抗原表位消化稳定性最高,但其表位多肽消化稳定性没有显著高于其它所有表位多肽,说明在消化过程中Pen a 1结构对该表位起到一定的保护作用,使其保持较高的消化稳定性;No.1、2、3次之,3个表位间无显著性差异;No.5消化稳定性最差,表明Pen a 1空间结构对其无明显保护作用。【结论】建立了一种用表位抗体检测过敏原经模拟消化后抗原表位消化稳定性的方法。Pen a 1经SGF消化后,免疫原性降低,分解生成部分较稳定的蛋白片段,但仍具有致敏性;5个抗原表位中No.4消化稳定最高,No.5最差。

关键词: Pen a 1, SGF, 抗原表位, 消化稳定性

Abstract: 【Objective】 Pen a 1 is a major allergen in shrimp, and its epitopes play a decisive role in allergic reactions. In order to evaluate the digestion stability of Pen a 1, the immunogenicity of Pen a 1 and its epitopes digested by simulated gastric fluid (SGF) was detected by antibodies of Pen a 1 and epitopes. It provided a theoretical basis for the study of the human digestive effects on Pen a 1 and the mechanism of desensitization food preparation.【Method】Pen a 1 was purified from Metapenaeus ensis. Five epitope peptides of Pen a 1 were synthesized using Fmoc Method. The peptides were conjugated to keyhole limpet (KLH) and bovine serum(BSA) to get artificial immunity and coating antigen, respectively. The tested serum was prepared by immuning New Zealand rabbits with Pen a 1 and the artificial immune. SGF was prepared according to the method of United States Pharmacopoeia. The changes of molecular weight of Pen a 1 was observed by SDS-PAGE and Tricine-SDS-PAGE. The capacity of IgE-binding of Pen a 1 and its epitope peptides by SGF digestion was analyzed by means of Western-blot qualitatively and ci-ELISA quantitatively.【Result】SDS-PAGE showed that Pen a 1 was degraded with increasing digestion time and generated a new 22 KD sensitization allergic protein. Tricine-SDS-PAGE showed that there were no protein fragments generated between 1.7-18 KD. Western-blot indicated that after the digestion of Pen a 1, the proteolytic fragments inordinately bound to six antibodies. Antibodies of Pen a 1 and No.4 bound to almost all proteolytic fragments. The fragment of 22 KD was resistant to digestion. This fragment bound to antibody No.3, 4, and 5 but almost no reaction to antibodies No.1, and 2, which indicated that the fragment carried No.3, 4, and 5 epitopes. The inhibition rate between Pen a 1 after SGF digestion and the antibodies tested by ci-ELISA was significantly decreased, indicating that the immunogenicity of Pen a 1 and its epitopes was decreased significantly. Moreover, the epitope peptides digested by SGF got the same result, but the digestion stability between epitopes of Pen a 1 and epitope peptides varied greatly: the epitopes of Pen a 1 was No.4>No.2>No.1> No.3>No.5, and there was no significant differences among No.3, 1, and 2; the epitope peptides was No.1> No.2> No.3>No.4>No.5, and there was no significant difference among No.2, 3, and 4. Combined with the results of Western-blot, No.4 epitope had the highest stability in SGF but the stability of No.4 peptide wasn’t higher than others significantly due to the protection of the spatial structure of Pen a 1. Stability of No.1, 2, and 3 was lower than No.4, and there was no significant differences between them. No.5 epitope showed rather rapid degradation in SGF than others.【Conclusion】The method for detection of digestibility of allergen and its epitopes using epitope antibodies was established. The immunogenicity of Pen a 1 after SGF digestion reduced significantly, but the generated fragments were still possible to cause hypersensitivity. No.4 epitope had the highest stability after SGF digestion, and No.5 epitope to SGF digestion was the most labile.

Key words: Pen a 1, SGF, epitopes, digestibility