Lanne B, Schierbeck B, Karlsson K A
Department of Medical Biochemistry, Göteborg University, Sweden.
J Biochem. 1994 Dec;116(6):1269-74. doi: 10.1093/oxfordjournals.jbchem.a124674.
The carboxyl group of the natural cholera toxin receptor, the ganglioside GM1, Gal beta 1-3GalNAc beta 1-4(NeuAc alpha 2-3)Gal beta 1-4Glc beta 1-Cer, has been converted to a number of C(1)-amides of NeuAc. The binding of cholera toxin B-subunit to these derivatives was monitored by exposing the modified glycolipids, on solid phases, to radiolabeled toxin. Binding was obtained, although substantially reduced, with the amide and to a lesser extent with the benzylamide and also the C(1)-alcohol. In the assay system used, the methyl-, ethyl-, or propylamides did not bind. It was concluded that the hydrogen bonding capacity of a carboxyl or amide group is needed for strong binding. This is in agreement with the recently published crystal structure of the B-subunit in complex with the GM1 pentasaccharide.
天然霍乱毒素受体神经节苷脂GM1（Galβ1-3GalNAcβ1-4(NeuAcα2-3)Galβ1-4Glcβ1-Cer）的羧基已被转化为多种NeuAc的C(1)-酰胺。通过将固相上的修饰糖脂暴露于放射性标记的毒素来监测霍乱毒素B亚基与这些衍生物的结合。尽管结合力大幅降低，但酰胺以及程度较轻的苄基酰胺和C(1)-醇仍能产生结合。在所使用的检测系统中，甲基、乙基或丙基酰胺不发生结合。得出的结论是，强结合需要羧基或酰胺基团的氢键结合能力。这与最近发表的B亚基与GM1五糖复合物的晶体结构一致。
