五龙鹅IgY、IgM分子特性研究

Studies on molecular properties of IgY and IgM of Wulong goose

为丰富和完善鹅Ig分子特性的研究，以层析、离子交换等方法分离纯化五龙鹅的免疫球蛋白及重链、轻链、Fab段、Fc段，进行鹅Ig的多态性、分子质量、氮基酸组成、稳定性等分子特性研究。结果表明：五龙鹅IgY存在几个亚类。总分子质量为166ku，重链约为60ku，轻链约为23．5ku；鹅IgM的重链分子质量分别为51．72、48．30和44．09ku，轻链20．30ku，所以，总分子质量约为660～740ku；五龙鹅Ig重链的分子质量均小于鸡、鸭；IgY的Fab段分子质量为48．67ku．Fc段为68．62ku。IgY的重链和轻链中碱性氮基酸摩尔分数小于酸性氮基酸，为酸性蛋白质．而IgM则为碱性蛋白质；IgY中Cys摩尔分数为2．25％，IgM为3．26％；鹅IgY的重链和轻链中Pro的摩尔分数相差较大．分别为7．69％和0．10％；鹅IgY在pH3．5～11．5的范围内十分稳定，IgM在pH4．0～10．5的范围内稳定，IgM的酸碱稳定性小于IgY，但在pH3．5～4．5时活性增加5％～8％；研究表明五龙鹅IgY热稳定性较差，热变性反应级数为1．2。

In order to enrich and improve our understanding of the molecular characteristics of geese Ig, we studied Ig （H＋ L）, H chain, L chain, Fab and Fc sections of Wulong goose, and molecular properties of Wulong goose Ig. Results indicated that the IgY molecular weight was 166 ku, H chain was about 60 ku, and L chain was about 23.5 ku. H chain molecular weight of IgM were 51.72 ku, 48.30 ku and 44.09 ku respectively and the L chain was 20.30 ku, hence, the molecular weight of IgM was about 660 - 740 ku. The molecular weight of Ig and H chain were smaller than that of chicken and duck; the molecular weight was 48.67 ku for Fab section and 68.62 ku for Fc section. There was more acid amino acid in IgY, H chain and L chain, and more alkaline amino acid in IgM, H chain and L chain. Therefore, IgY was an acid protein and IgM was an alkaline protein. The mol percentage of Cys was 2.25% in IgY, and 3.26% in IgM;mol percentage of Pro was 7.69% and 0.10% in H and L chain of IgY, and the difference was significant. The stability of IgY in acid and alkali was very steady in the pH range of 3.5 to 11, that of IgM in pH range of 4.0 to 10.5, but worse than IgY, and the activity of IgM increased 5% -8% at pH3.5- 4.5; the heat stability of goose IgY was poorer than that of cattle and pig, and the reaction class of IgY was 1.2.