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Intra-intestinal kinetics and absorption mechanism of digestion-resisitant maclomolecular food components

难消化大分子食物成分的肠内动力学及吸收机制

基本信息

批准号：
14360073
负责人：
MATSUDA Tsukasa
金额：
$ 9.54万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

Egg albumin (ovalbumin:OVA) is resistant to proteolytic hydrolysis and known to be a major allergenic protein in egg allergy. By using egg albumin as a model macromoleculer food component, the absorption of OVA from mouse intestinal tract into body and the kinetics of OVA in circulating peripheral blood were investigated. After oral administration of OVA (10 mg) to mice, peripheral blood was collected and then serum was separated from coagulated blood. The OVA concentration in the serum was determined to be 10-50 ng/ml by EUSA, and the OVA in the serum was concentrated by immuno-affinity precipitation using anti-OVA antibodies coupled to Sepharose. In SDS-PAGE analysis, the OVA recovered from peripheral blood revealed a single major protein band with a molecular mass identical to intact OVA and a minor band with a slightly smaller molecular mass. No band corresponding to OVA fragments with smaller molecular masses, which had been demonstrated to be the major components of OVA antigens in the mouse small intestine. Furthermore, two-dimensional gel electrophoresis demonstrated that the OVA recovered from blood was composed of 4-6 protein spots with different pI but with the same molecular mass, and that the basic protein spots were dominant as compared with those of intacl OVA, suggesting that the pI of OVA was shifted to more basic ones during the intestinal absorption or the migration in circulating blood. Such a pI shift was not observed for OVA incubated in vitro with mouse serum. Taken together, it is suggested that a small portion of orally administered OVA could escape from intestinal proteolytic digestion and be absorbed as an intact form, but with a slight modification, across intestinal epithelium into the blood stream. Thus, it might be possible that orally administered bio-active proteins exert its biological function in peripheral tissues and organs.

卵清蛋白（ovalbumin：OVA）是一种抗蛋白水解的蛋白质，已知是鸡蛋过敏的主要过敏原蛋白。以卵清蛋白为模型高分子食品成分，研究了卵清蛋白在小鼠肠道的吸收及在外周血中的动力学。在对小鼠口服给予OVA（10 mg）后，收集外周血，然后从凝固的血液中分离血清。通过EUSA测定血清中的OVA浓度为10-50 ng/ml，并使用偶联到Sepharose的抗-OVA抗体通过免疫亲和沉淀浓缩血清中的OVA。在SDS-PAGE分析中，从外周血中回收的OVA显示分子量与完整OVA相同的单一主要蛋白条带和分子量略小的次要条带。没有对应于具有较小分子量的OVA片段的条带，其已被证明是小鼠小肠中OVA抗原的主要组分。双向凝胶电泳结果表明，从血液中回收的卵清蛋白由4-6个pI不同但分子量相同的蛋白质斑点组成，与完整的卵清蛋白相比，碱性蛋白质斑点占优势，表明卵清蛋白在肠道吸收或在循环血液中迁移时pI向碱性蛋白质转移。在体外与小鼠血清孵育的OVA中未观察到这种pI偏移。综上所述，这表明一小部分口服给药的OVA可以从肠道蛋白水解消化中逃逸，并以完整的形式被吸收，但经过轻微的修饰，穿过肠上皮进入血流。因此，口服给药的生物活性蛋白可能在外周组织和器官中发挥其生物学功能。