粘蛋白
化学
生物物理学
水溶液
粘液
分子
原子力显微镜
浊度法
球状蛋白
结晶学
生物化学
纳米技术
有机化学
材料科学
生物
生态学
作者
Zhenning Hong,B. Chasan,Rama Bansil,Bradley S. Turner,K. Ramakrishnan Bhaskar,Nezam H. Afdhal
出处
期刊:Biomacromolecules
[American Chemical Society]
日期:2005-10-26
卷期号:6 (6): 3458-3466
被引量:127
摘要
Mammalian gastric mucin, at high concentration, is known to form a gel at low pH, behavior essential to the protection of the stomach from auto-digestion. Atomic force microscopy (AFM) measurements of dilute solutions of porcine gastric mucin in an aqueous environment in the pH range 6−2 provide a direct visualization of extended fiberlike molecules at pH 6 that aggregate at pH 4 and below forming well-defined clusters at pH 2. The clusters consist of 10 or less molecules. AFM images of mucin at high concentration at pH 2 reveal clusters similar to those seen in the dilute solutions at low pH. We also imaged human gastric mucus revealing a network having a “pearl necklace” structure. The “pearls” are similar in size to the clusters found in the purified porcine gastric mucin gels. AFM images of deglycosylated mucin reveal that the deglycosylated portions of the molecule re-fold into compact, globular structures suggesting that the oligosaccharide chains are important in maintaining the extended conformation of mucin. However, the oligosaccharides do not appear to be directly involved in the aggregation at low pH, as clusters of similar size are observed at pH 2 in both native and deglycosylated mucin.
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