Mansour M H, Negm H I, Saad A H, Taalab N I
Department of Zoology, Faculty of Science, Cairo University, Egypt.
Mol Biochem Parasitol. 1995 Feb;69(2):173-84. doi: 10.1016/0166-6851(94)00188-s.
Two novel lectins that bind selectively to a schistosome-associated fucosyllactose-related determinant have been characterized and purified from the hemolymph of Biomphalaria alexandrina, the snail vector of Schistosoma mansoni. Both lectins were purified by affinity chromatography on a column of equimolar mixture of D- and L-glucose coupled to epoxy-activated Sepharose 6B and sequential elution by D-glucose (designated BaSI) and L-fucose (designated BaSII). Assessment of the structural characteristics, by one- and two-dimensional polyacrylamide gel electrophoresis, indicated that BaSI and BaSII were structurally distinct, and exist in their native forms as multimers of non-covalently associated subunits, that were of different sizes in BaSI and of equal size in BaSII. Removal of N-linked glycans by Endo-beta-N-acetylglucosaminidase F resolved the heterodisperse pattern of BaSI subunits into two spots of 13.2 kDa (pI 7.2) and 10.1 kDa (pI 5.8), and collapsed the acidic charge microheterogeneity of the BaSII subunit into a single spot that corresponded in terms of molecular weight and pI to the basic 13.2-kDa subunit of BaSI. In miracidial binding and inhibition assays with different sugars, both lectins exhibited selectivity towards a fucosyllactose sequence, but BaSII had a higher binding preference to fucose moieties. BaSII-Sepharose 4B affinity chromatography and analysis on two-dimensional gels indicated that multiple copies of the fucosyllactose-related determinant were expressed by heterogeneous, acidic glycoproteins in the miracidial stage of S. mansoni.
已从曼氏血吸虫的螺蛳宿主埃及扁卷螺的血淋巴中鉴定并纯化出两种新型凝集素，它们能选择性结合与血吸虫相关的岩藻糖基乳糖相关决定簇。两种凝集素通过在与环氧活化的琼脂糖凝胶6B偶联的D-葡萄糖和L-葡萄糖等摩尔混合物柱上进行亲和层析进行纯化，并依次用D-葡萄糖（命名为BaSI）和L-岩藻糖（命名为BaSII）洗脱。通过一维和二维聚丙烯酰胺凝胶电泳对结构特征进行评估，结果表明BaSI和BaSII在结构上不同，以非共价结合亚基的多聚体形式以天然形式存在，在BaSI中大小不同，在BaSII中大小相同。用内切β-N-乙酰葡糖胺酶F去除N-连接聚糖后，BaSI亚基的异质分散模式分解为13.2 kDa（pI 7.2）和10.1 kDa（pI 5.8）的两个斑点，BaSII亚基的酸性电荷微异质性聚合成一个斑点，其分子量和pI与BaSI的碱性13.2 kDa亚基相对应。在与不同糖类的毛蚴结合和抑制试验中，两种凝集素均对岩藻糖基乳糖序列表现出选择性，但BaSII对岩藻糖部分的结合偏好更高。BaSII-琼脂糖凝胶4B亲和层析和二维凝胶分析表明，在曼氏血吸虫毛蚴阶段，多种与岩藻糖基乳糖相关的决定簇由异质酸性糖蛋白表达。
