Matrosovich M N, Gambaryan A S, Chumakov M P
Institute of Poliomyelitis and Viral Encephalitides, Russian Academy of Medical Sciences, Moscow Region.
Virology. 1992 Jun;188(2):854-8. doi: 10.1016/0042-6822(92)90541-v.
Equine alpha 2-macroglobulin (EM), known to contain both Neu5Ac and Neu4,5Ac2 sialic acid residues, was treated with Vibrio cholerae sialidase for the selective removal of Neu5Ac and was compared with the untreated EM for its binding by a panel of influenza viruses. Type A H3N2 virus strains having Leu in position 226 of their hemagglutinin (HA) changed the affinity for sialidase-treated EM only slightly, if at all, indicative of their ability to bind the 4-O-Ac-substituted Neu5Ac receptor determinant. At the same time, all B and H1N1 viruses, some H2N2 variants, as well as H3N2 strains with 226 Gln studied were unable to recognize Neu4,5Ac2 moieties of EM. Molecular modeling based on the known 3-D structure of H3 HA complexed with sialyllactose (Weis et al. (1988) Nature 333, 426-431) predicts that the 4-O-Ac substituent of sialic acid would protrude with its carbonyl oxygen inside the receptor-binding site of HA, thus possibly interfering with binding.
已知马α2-巨球蛋白（EM）同时含有N-乙酰神经氨酸（Neu5Ac）和N-乙酰基-4,5-二神经氨酸（Neu4,5Ac2）唾液酸残基，用霍乱弧菌唾液酸酶处理以选择性去除Neu5Ac，并将其与未处理的EM进行比较，观察一组流感病毒对其的结合情况。在血凝素（HA）第226位具有亮氨酸的甲型H3N2病毒株，对唾液酸酶处理后的EM的亲和力即使有变化也非常小，这表明它们能够结合4-O-乙酰基取代的Neu5Ac受体决定簇。与此同时，所有的乙型和H1N1病毒、一些H2N2变体以及所研究的在226位具有谷氨酰胺的H3N2毒株，都无法识别EM的Neu4,5Ac2部分。基于与唾液乳糖复合的H3 HA已知三维结构进行的分子模拟（魏斯等人（1988年）《自然》333卷，426 - 431页）预测，唾液酸的4-O-乙酰基取代基将以其羰基氧突出于HA的受体结合位点内，从而可能干扰结合。
