Negm H I
Department of Zoology, Faculty of Science, Monoufia University, Shebin El Kom, Egypt.
Dev Comp Immunol. 1996 Mar-Apr;20(2):87-96. doi: 10.1016/0145-305x(95)00041-q.
Utilizing a Biomphalaria alexandrina-derived lectin (BaSII) of proven specificity to a Schistosoma mansoni-associated fucosyllactose [(Fuc alpha 1-2) Gal beta 1-4 Glc] determinant, two determinant-bearing glycoproteins of 40 and 37 kDa were found to be synthesized by the cercarial stage of the parasite. The two glycoproteins were isolated by BaSII affinity column chromatography from extracts of cercariae metabolically radiolabelled with 35S-methionine. Treatments with endoglycosidases, alkaline borohydride, as well as concanavalin A column chromatography and analysis by two-dimensional gels indicated that the two glycoproteins are synthesized as a single 33 kDa polypeptide backbone that is differentially glycosylated with one and/or two determinant-bearing N-linked complex-type glycan units of either the biantennary, or, to a lesser extent, the tri- or tetra-antennary types. The two glycoproteins lack other conventional high mannose-type or O-linked glycans, and the distinct structures of the complex-type oligosaccharides accounted solely for the expression of three isomorphs for each determinant-bearing glycoprotein. Based on the structural relatedness of the fucosyllactose determinant to the antigenic mammalian blood group H trisaccharide, our observations may have implications in mechanisms of host-parasite interactions as well as immunoprophylaxis.
利用一种已证实对曼氏血吸虫相关岩藻糖基乳糖[（Fucα1-2）Galβ1-4Glc]决定簇具有特异性的亚历山大双脐螺来源的凝集素（BaSII），发现该寄生虫的尾蚴阶段合成了两种带有该决定簇的糖蛋白，分子量分别为40 kDa和37 kDa。通过BaSII亲和柱色谱法从用35S-甲硫氨酸进行代谢放射性标记的尾蚴提取物中分离出这两种糖蛋白。用内切糖苷酶、碱性硼氢化钠处理，以及伴刀豆球蛋白A柱色谱法和二维凝胶分析表明，这两种糖蛋白是作为单一的33 kDa多肽骨架合成的，该骨架被一个和/或两个带有决定簇的N-连接复合型聚糖单元进行了差异糖基化，这些聚糖单元为双天线型，或者在较小程度上为三天线型或四天线型。这两种糖蛋白缺乏其他常规的高甘露糖型或O-连接聚糖，复合型寡糖的独特结构仅导致了每种带有决定簇的糖蛋白出现三种同形体。基于岩藻糖基乳糖决定簇与抗原性哺乳动物血型H三糖的结构相关性，我们的观察结果可能对宿主-寄生虫相互作用机制以及免疫预防具有启示意义。
