Wu A M, Song S C, Wu J H, Pfüller U, Chow L P, Lin J Y
Glyco-Immunochemistry Research Laboratory, Institute of Molecular and Cellular Biology, Kwei-san, Taiwan.
Biochim Biophys Acta. 1995 Jan 18;1243(1):124-8. doi: 10.1016/0304-4165(94)00132-h.
The binding properties of a glycoprotein with blood group P1 specificity isolated from sheep hydatid cyst fluid with Gal and GalNAc specific lectins was investigated by quantitative precipitin and precipitin inhibition assays. The glycoprotein completely precipitated Ricinus communis agglutinin (RCA1), Abrus precatorius agglutinin (APA) and Mistletoe toxic lectin-I (ML-I). Only 1.0 microgram of P1 glycoprotein was required to precipitate 50% of 5.1 micrograms ML-I nitrogen. It also reacted well with abrin-a and ricin, precipitating over 73% of the lectin nitrogen added, but poorly or weakly with Dolichos biflorus (DBL), Vicia villosa (VVL, a mixture of A4, A2B2 and B4), VVL-B4, Arachis hypogaea (PNA), Maclura pomifera (MPL), Bauchinia purpurea alba (BPL) and Wistaria floribunda (WFL) lectins. When an inhibition assay in the range of 5.1 micrograms N to 5.9 micrograms N of lectins (ML-I, abrin-a; ricin, RCA1, and APA, and 10 micrograms P1 active glycoprotein interaction was performed; from 76 to 100% of the precipitations were inhibited by 0.44 and 0.52 mumol of Gal alpha 1-->4Gal and Gal beta 1-->4GlcNAc, respectively, but not or insignificantly with 1.72 mumol of GlcNAc. The Gal alpha 1-->4Gal disaccharide found in this P1 active glycoprotein is a frequently occurring sequence of many glycosphingolipids located at the surface of mammalian cell membranes, especially human erythrocytes and intestinal cells for ligand binding and microbial toxin attachment. The present finding suggests that the Gal alpha 1-->4Gal beta 1-->4GlcNAc sequence in this P1 active glycoprotein is one of the best glycoprotein receptors for three toxic lectins (ricin, abrin-a, and ML-I) as well as for APA, and RCA1, and the result of inhibition assay implies that these lectins are recognizing part or all of the Gal alpha 1-->4Gal beta 1-->4GlcNAc sequence in the P1 active glycoprotein.
通过定量沉淀和沉淀抑制试验，研究了从绵羊包虫囊肿液中分离出的具有血型P1特异性的糖蛋白与半乳糖（Gal）和N-乙酰半乳糖胺（GalNAc）特异性凝集素的结合特性。该糖蛋白能完全沉淀蓖麻凝集素（RCA1）、相思子凝集素（APA）和槲寄生毒凝集素-I（ML-I）。仅需1.0微克P1糖蛋白就能沉淀5.1微克ML-I氮的50%。它与相思子毒素-a和蓖麻毒素反应也良好，能沉淀添加的凝集素氮的73%以上，但与双花扁豆（DBL）、蚕豆（VVL，A4、A2B2和B4的混合物）、VVL-B4、花生（PNA）、桑橙（MPL）、白花紫芸英（BPL）和紫藤（WFL）凝集素反应较差或较弱。当进行凝集素（ML-I、相思子毒素-a、蓖麻毒素、RCA1和APA）在5.1微克氮至5.9微克氮范围内以及10微克P1活性糖蛋白相互作用的抑制试验时；分别用0.44和0.52微摩尔的α-半乳糖基-1→4-半乳糖（Galα1→4Gal）和β-半乳糖基-1→4-N-乙酰葡糖胺（Galβ1→4GlcNAc）可抑制76%至100%的沉淀，但1.72微摩尔的N-乙酰葡糖胺则无抑制作用或抑制作用不明显。在这种P1活性糖蛋白中发现的α-半乳糖基-1→4-半乳糖二糖是许多位于哺乳动物细胞膜表面的糖鞘脂中常见的序列，尤其是人红细胞和肠道细胞，用于配体结合和微生物毒素附着。目前的发现表明，这种P1活性糖蛋白中的α-半乳糖基-1→4-半乳糖基-1→4-N-乙酰葡糖胺序列是三种毒性凝集素（蓖麻毒素、相思子毒素-a和ML-I）以及APA和RCA1的最佳糖蛋白受体之一，抑制试验结果表明这些凝集素识别P1活性糖蛋白中α-半乳糖基-1→4-半乳糖基-1→4-N-乙酰葡糖胺序列的部分或全部。
