牛初乳免疫球蛋白 A的纯化与原子力显微镜观测  

Purification of secretory immunoglobulin A from bovine colostrum and detection by atomic force microscopy

作　　者：傅骁勇[1] 谭璐[1] 徐敬[2] 朱国栋[2] 李杰[2] 王红阳[1] 

机构地区：[1]第二军医大学东方肝胆外科医院国际合作生物信号转导研究中心,上海200438 [2]同济大学物理系波尔固体物理研究所

出　　处：《第二军医大学学报》2004年第1期108-110,共3页Academic Journal of Second Military Medical University

基　　金：国家自然科学基金 ( 3 0 170 2 2 5 )

摘　　要：目的 :纯化牛初乳免疫球蛋白 A(Ig A)并在原子力显微镜 (AFM)下进行观测。 方法 :应用逐级盐析、透析和离子交换层析等生化手段 ,从牛初乳中提取 Ig A,SDS- PAGE鉴定纯化结果。应用 AFM对吸附在新剥离云母或多聚赖氨酸 (PL L)处理云母片基上的 Ig A进行空气相的结构观测。 结果 :考马斯亮蓝染色鉴定纯化的蛋白含有重链、轻链和分泌片 ;正常生理条件下的 Ig A以寡聚体结构为主 ,单体大约 2 .6 nm× 1 8.0 nm× 2 0 .2 nm,与电镜结果基本吻合 ;Ig A在 PL L 处理云母片基上的吸附呈现树枝状聚集 ,随孵育时间的延长 ,聚集现象更趋明显。 结论 :结合生化方法和 AFM观测 ,可对 Ig A等免疫球蛋白分子进行天然结构状态的微观探测 。Objective:To purify secretory immunoglobulin A(IgA) from bovine colostrums and to detect it by atomic force microscopy(AFM).Me thods :IgA was purified by salt out, dialysis and ion exchange chromatography, and identifie d by SDS PAGE. Molecular structure of IgA was observed on freshly cleaved mica or PLL treated mica by AFM in air. Results:SDS PAGE analysis follo wed by Coomassie blu e staining revealed secretory piece, heavy and light chain constituted the purif ied IgA. Under AFM, IgA existed mainly in oligomer form i n the physiological condition. The monomer's dimension with 2.6 nm×18.0 nm×20. 2 nm coincided with the result discerned by electronmicroscopy. The attachment o f IgA on PLL treated mica showed dendritic aggregation form. This aggregation ph enomenon tended to be more obvious with prolonging incubation time. Conclusion:It is feasible to observe the microstructure of immun oglobulin in natural condition by combination of biochemistry and atomic force m icroscop y techniques,which may provide an effective pathway for the study of IgA structure, contributing to functional reg ulation of micromoleculars.

关 键 词：牛初乳 免疫球蛋白A 纯化 原子力显微镜 观测 生理调控 

分 类 号：Q512.2[生物学—生物化学]