Schwertmann A, Schroten H, Hacker J, Kunz C
Research Institute of Child Nutrition, Dortmund, Germany.
J Pediatr Gastroenterol Nutr. 1999 Mar;28(3):257-63. doi: 10.1097/00005176-199903000-00009.
Escherichia coli (E. coli) strains, expressing S-fimbriae, belong to the most common gram-negative pathogens that cause sepsis and meningitis in neonates. The attachment of S-fimbriae to the cell surface is mediated by membrane glycoconjugates, which often carry N-acetylneuraminic acid.
Binding studies were performed with glycoproteins from the whey fraction of human milk to investigate whether they exert a potential inhibitory effect on bacterial adhesion. Whey glycoproteins were separated according to their molecular weight by fast protein liquid chromatography gel filtration. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis, proteins were transferred to nitrocellulose membranes and incubated with isolated S-fimbriae from recombinant E. coli strain HB 101 (pANN 801-4).
S-fimbriae recognized four whey proteins with a molecular mass of more than 200 kDa, 170 to 150 kDa, and 80 kDa. Their glycosylation pattern was investigated using the lectins Sambucus nigra, Maackia amurensis, Galanthus nivalis, and Arachis hypogaea. Thus the presence of N- and O-glycans in these proteins was confirmed. The preferential binding to N-acetylneuraminic acid containing glycoproteins was demonstrated by a complete abolishment of these reactions by incubation with acidic lactose-derived oligosaccharides. However, the cleavage of N-acetylneuraminic acid from glycoproteins by mild acid hydrolysis revealed a second binding site for S-fimbriae on milk proteins of a similar molecular weight range. Terminal galactose in human milk glycoconjugates were thought to react with S-fimbriae as well.
These data further support the opinion that glycoproteins from human milk are potential receptor analogues for certain bacteria that may prevent microbial adhesion to the epithelial cell surface.
表达S菌毛的大肠杆菌菌株是导致新生儿败血症和脑膜炎的最常见革兰氏阴性病原体。S菌毛与细胞表面的附着由膜糖缀合物介导，膜糖缀合物通常携带N-乙酰神经氨酸。
用人乳乳清部分的糖蛋白进行结合研究，以调查它们是否对细菌粘附具有潜在的抑制作用。通过快速蛋白质液相色谱凝胶过滤根据分子量分离乳清糖蛋白。在十二烷基硫酸钠-聚丙烯酰胺凝胶电泳后，将蛋白质转移到硝酸纤维素膜上，并与重组大肠杆菌菌株HB 101（pANN 801-4）分离的S菌毛孵育。
S菌毛识别出四种分子量超过200 kDa、170至150 kDa和80 kDa的乳清蛋白。使用黑接骨木、黑水苏、雪花莲和花生凝集素研究了它们的糖基化模式。从而证实了这些蛋白质中存在N-聚糖和O-聚糖。通过与酸性乳糖衍生的寡糖孵育完全消除这些反应，证明了对含N-乙酰神经氨酸的糖蛋白的优先结合。然而，通过温和酸水解从糖蛋白中裂解N-乙酰神经氨酸揭示了S菌毛在类似分子量范围内的乳蛋白上的第二个结合位点。人乳糖缀合物中的末端半乳糖也被认为与S菌毛反应。
这些数据进一步支持了以下观点，即人乳中的糖蛋白是某些细菌的潜在受体类似物，可能会阻止微生物粘附到上皮细胞表面。
