Couto A S, Gonçalves M F, Colli W, de Lederkremer R M
Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina.
Mol Biochem Parasitol. 1990 Feb;39(1):101-7. doi: 10.1016/0166-6851(90)90012-b.
The structure of the N-linked oligosaccharide of the 85-kDa surface glycoprotein (Tc-85) from the infective trypomastigote form of Trypanosoma cruzi was investigated. Tc-85 metabolically labeled with [14C]glucose was purified by affinity chromatography on wheat germ agglutinin-Sepharose. Binding to the lectin was lost on treatment of Tc-85 with neuraminidase. The N-linked asialo-oligosaccharide was released by endo-beta-N-acetylglucosaminidase F digestion of asialo-Tc-85 and was further analyzed using specific exoglycosidases. [14C]fucose was detected after alpha-L-fucosidase treatment or mild acid hydrolysis. The afucosyl oligosaccharide was 3H-labeled by the galactose oxidase-NaB3H4 method. [3H]Galactose was released by alpha-galactosidase, and only then was beta-galactosidase effective in removing another galactose. The gal(alpha 1-3)gal unit was demonstrated by periodate oxidation studies on the [3H]galactose-labeled asialo-glycoprotein. The presence of gal(alpha 1-3)gal in Tc-85 could be related to the recent finding of elevated antibody levels against this epitope in patients with Chagas' disease.
对克氏锥虫感染性锥鞭毛体形式的85 kDa表面糖蛋白（Tc - 85）的N - 连接寡糖结构进行了研究。用[14C]葡萄糖进行代谢标记的Tc - 85通过在麦胚凝集素 - 琼脂糖上的亲和层析进行纯化。用神经氨酸酶处理Tc - 85后，其与凝集素的结合丧失。通过内切β - N - 乙酰葡糖胺酶F消化去唾液酸的Tc - 85释放出N - 连接的去唾液酸寡糖，并使用特异性外切糖苷酶进一步分析。用α - L - 岩藻糖苷酶处理或温和酸水解后检测到[14C]岩藻糖。通过半乳糖氧化酶 - NaB3H4方法对去岩藻糖基寡糖进行3H标记。α - 半乳糖苷酶释放出[3H]半乳糖，只有在此之后β - 半乳糖苷酶才能有效地去除另一个半乳糖。通过对[3H]半乳糖标记的去唾液酸糖蛋白进行高碘酸盐氧化研究证实了半乳糖（α1 - 3）半乳糖单元的存在。Tc - 85中半乳糖（α1 - 3）半乳糖的存在可能与最近在恰加斯病患者中发现针对该表位的抗体水平升高有关。
