Sujino K, Jackson R J, Chan N W, Tsuji S, Palcic M M
Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada,
Glycobiology. 2000 Mar;10(3):313-20. doi: 10.1093/glycob/10.3.313.
The substrate specificity of an alpha2,3-sialyltransferase (v-ST3Gal I) obtained from myxoma virus infected RK13 cells has been determined. Like mammalian sialyltransferase enzymes, the viral enzyme contains the characteristic L- and S-sialyl motif sequences in its catalytic domain. Analysis of the deduced amino acid sequences of cloned sialyltransferases suggests that v-ST3Gal I is closely related to mammalian ST3Gal IV. v-ST3Gal I catalyzes the transfer of sialic acid from CMP-NeuAc to Type I (Galbeta1-3GlcNAcbeta) II (Galbeta1-4GlcNAcbeta) and III (Galbeta1-3GalNAcbeta) acceptors. In addition, the viral enzyme also transfers sialic acid to the fucosylated acceptors Lewis(x) and Lewis(a). This substrate specificity is unlike any sialyltransferases described to date, though it is most comparable with those of mammalian ST3Gal IV enzymes. The products from reactions with fucosylated acceptors were characterized by capillary zone electrophoresis, (1)H-NMR spectroscopy and mass spectrometry. They were shown to be 2,3-sialylated Lewis(x) and 2,3-sialylated Lewis(a), respectively.
已确定从感染黏液瘤病毒的RK13细胞中获得的α2,3-唾液酸转移酶（v-ST3Gal I）的底物特异性。与哺乳动物唾液酸转移酶一样，该病毒酶在其催化结构域中含有特征性的L-和S-唾液酸基序序列。对克隆的唾液酸转移酶推导氨基酸序列的分析表明，v-ST3Gal I与哺乳动物ST3Gal IV密切相关。v-ST3Gal I催化唾液酸从CMP-NeuAc转移到I型（Galβ1-3GlcNAcβ）、II型（Galβ1-4GlcNAcβ）和III型（Galβ1-3GalNAcβ）受体。此外，该病毒酶还将唾液酸转移到岩藻糖基化受体Lewis(x)和Lewis(a)上。这种底物特异性不同于迄今为止描述的任何唾液酸转移酶，尽管它与哺乳动物ST3Gal IV酶的底物特异性最为相似。与岩藻糖基化受体反应的产物通过毛细管区带电泳、1H-NMR光谱和质谱进行了表征。结果表明它们分别是2,3-唾液酸化的Lewis(x)和2,3-唾液酸化的Lewis(a)。
