Krusius T, Fukuda M, Dell A, Ruoslahti E
J Biol Chem. 1985 Apr 10;260(7):4110-6.
Human amniotic fluid fibronectin was found to contain three types of carbohydrates: complex-type N-glycosidic glycans, lactosaminoglycans, and O-glycosidic glycans. The structures of the complex-type glycans were established by carbohydrate and methylation analysis, Smith degradation, sequential exoglycosidase treatments, lectin chromatography, and DEAE-Sephadex chromatography. Lactosaminoglycans were analyzed by fast atom bombardment mass spectrometry, and the O-glycosidically-linked oligosaccharides by gas-liquid chromatography-mass spectrometry and high-pressure liquid chromatography. The results show that amniotic fluid fibronectin contains 2 mol of biantennary and 2-3 mol of triantennary, complex-type N-glycosidic glycans. Unlike the N-glycosidic glycans of human adult plasma fibronectin, which contain only traces of fucose and are completely sialylated, the glycans from amniotic fluid fibronectin are fucosylated and only partially sialylated. The complex-type N-glycosidic glycans present in amniotic fluid fibronectin also include a fractional amount (0.1 mol) of glycans with a polylactosaminyl structure. In addition, 4 mol of O-glycosidic oligosaccharides, which have not previously been described in fibronectins, were found in amniotic fluid fibronectin. The major oligosaccharides in this fraction have the structures Gal beta 1----3GalNAcol, NeuNAc alpha 2----3Gal beta 1----3GalNAcol and NeuNAc alpha 2----3Gal beta 1----3(NeuNAc alpha 2----6)GalNAcol. O-glycosidically linked oligosaccharides were also detected in human adult plasma fibronectin but in smaller amounts than in amniotic fluid fibronectin. These results show that amniotic fluid fibronectin differs from plasma fibronectin with regard to the number of glycans attached to the polypeptide and that the glycans present in these two fibronectins differ in structure.
复合型N-糖苷聚糖、乳糖胺聚糖和O-糖苷聚糖。通过碳水化合物和甲基化分析、史密斯降解、外切糖苷酶连续处理、凝集素色谱法和二乙氨基乙基葡聚糖（DEAE - Sephadex）色谱法确定了复合型聚糖的结构。通过快原子轰击质谱法分析乳糖胺聚糖，通过气液色谱 - 质谱联用和高压液相色谱法分析O-糖苷连接的寡糖。结果表明，羊水纤连蛋白含有2摩尔的双天线型和2 - 3摩尔的三天线型复合型N-糖苷聚糖。与成人血浆纤连蛋白的N-糖苷聚糖不同，成人血浆纤连蛋白仅含有痕量岩藻糖且完全被唾液酸化，羊水纤连蛋白的聚糖被岩藻糖基化且仅部分被唾液酸化。羊水纤连蛋白中存在的复合型N-糖苷聚糖还包括少量（0.1摩尔）具有聚乳糖胺基结构的聚糖。此外，在羊水纤连蛋白中发现了4摩尔以前在纤连蛋白中未被描述过的O-糖苷寡糖。该部分中的主要寡糖具有Galβ1----3GalNAcol、NeuNAcα2----3Galβ1----3GalNAcol和NeuNAcα2----3Galβ1----3(NeuNAcα2----6)GalNAcol的结构。在成人血浆纤连蛋白中也检测到了O-糖苷连接的寡糖，但含量比羊水纤连蛋白中的少。这些结果表明，羊水纤连蛋白与血浆纤连蛋白在连接到多肽上的聚糖数量方面存在差异，并且这两种纤连蛋白中存在的聚糖在结构上也有所不同。
