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Studies on Protein Structure and Physiological Function of Ovalbumin with Property of Molecular Chaperon

具有分子伴侣性质的卵清蛋白的蛋白质结构和生理功能研究

基本信息

批准号：
13660301
负责人：
SUGIMOTO Yasushi
金额：
$ 2.24万
依托单位：
Kagoshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Ovalbumin, which is the major albumen protein having carbohydrate and phosphate residues, belongs to the serine protease inhibitor superfamily. However, ovalbumin is not inhibitory against proteases, and, therefore, its function remains uncertain except for a possible contribution as a nutrient source. We reported previously that ovalbumin molecules were transported from albumen to the embryo via egg yolk, amniotic fluid, serum etc, without degradation, and distributed in various organs including the central nervous system, while these molecules undergo changes in secondary conformation and attain a heat-stable state (this state of molecules will be called 'HS-ovalbumin'). Here we showed that HS-ovalbumin is distinguishable from the known heat-stable molecular form named S-ovalbumin by a presently prepared monoclonal antibody and that HS-ovalbumin arises from its native form (N-ovalbumin) in developing eggs. We also established in vitro culture conditions, under which embryos isolated from eggs at and after stage 4 of embryogenesis could be successfully cultured for at least 24 h. When the remnant fractions of endogenous ovalbumin was neutralized by using a polyclonal antibody, the isolated embryos could not grow normally, being particularly irregular in the brain tissue, which hardly undergo the neural tube closure occurring in normal embryos at stage 9. The embryos were rescued from the aberration by adding an excess amount of ovalbumin to the medium at an early period of culture. HS-ovalbumin showed a higher rescue rate than the N-and S-counterparts. Our findings demonstrated that ovalbumin is indispensable to, and probably plays a crucial role in, the embryonic organogenesis.

卵清蛋白属于丝氨酸蛋白酶抑制剂超家族，是一种主要的蛋白质，含有糖和磷酸残基。然而，卵清蛋白对蛋白酶没有抑制作用，因此，除了作为营养源的可能贡献外，其功能仍然不确定。我们以前报道过卵清蛋白分子从蛋清经卵黄、羊水、血清等运输到胚胎中，不降解，分布在包括中枢神经系统在内的各种器官中，同时这些分子经历二级构象的变化并达到热稳定状态（这种分子状态将被称为'HS-卵清蛋白'）。在这里，我们表明，HS-卵白蛋白是区别于已知的热稳定的分子形式命名为S-卵白蛋白由目前制备的单克隆抗体和HS-卵白蛋白产生于其天然形式（N-卵白蛋白）在发展中的鸡蛋。我们还建立了体外培养条件，在此条件下，从胚胎发生第4阶段和之后的卵中分离的胚胎可以成功地培养至少24 h。当内源性卵清蛋白的残余部分通过使用多克隆抗体被中和时，分离的胚胎不能正常生长，在脑组织中特别不规则，其几乎不经历在第9阶段正常胚胎中发生的神经管闭合。通过在培养早期向培养基中加入过量的卵清蛋白，可将胚胎从畸变中拯救出来。HS-卵清蛋白显示出比N-和S-对应物更高的拯救率。我们的研究结果表明，卵清蛋白是必不可少的，并可能发挥了关键作用，胚胎器官发生。