Regulation of glycolipid expression and its disorder

对合成活性神经节苷脂的唾液酸基转移酶进行了分离和鉴定。[1]唾液酸转移酶的高灵敏非放射性测定方法：为了改进神经节苷脂唾液酸转移酶活性的测定方法，我们使用了吡啶胺标记的寡糖作为底物，这些荧光底物在高效液相色谱中分离良好，适用于唾液酸转移酶的测定。神经节苷脂被内糖神经酰胺酶消化，释放的寡糖用吡啶胺标记。唾液酸转移酶是从大鼠肝脏高尔基体膜组分中部分纯化出来的。吡啶胺标记的GM3寡糖作为天然的GM3神经节苷脂是GD3合成酶的良好底物。但是，吡啶胺标记的CDH寡糖是GM3合成酶的较差底物。洗涤剂对GD3合酶全部活性的需求减少，这表明洗涤剂不仅作为酶的增溶剂，而且还提高了糖脂的利用率[2]P…唾液酸基转移酶的光亲和力标记：作为唾液酸转移酶(GM3合成酶)底物的乳糖基神经酰胺的光活性二氮杂环丙烷衍生物和CMP-NeuAc。这些化合物都是很好的底物，对GM3合成酶有很高的亲和力。这些化合物特异性地标记了一些分子，并用SDS-PAGE放射自显影进行了检测。[3]研究了非洲爪哇发育过程中神经节苷脂的特性和生物合成：非洲爪哇早期发育过程中神经节苷脂种类的变化。卵母细胞中的主要神经节苷脂是GalNAc-GM1b。GalNAc-GM1b的体内合成有两条可能的途径。UDP-GalNAc：GM1bβ1-3N-乙酰半乳糖胺转移酶活性仅在非洲爪蛙膜组分中检测到。这些结果表明，GalNAc-GM1b是由非洲爪蛙神经节四糖神经酰胺通过GM1b合成的。受精后GalNAc-GM1b和GM3水平显著升高。几条证据表明，α2-3唾液酸基转移酶活性在这一阶段升高。较少

Isolation and characterization of sialyltransferases which synthesize bioactive gangliosides were carried out.[1] High sensitive and non-radioactive assay method for sialyltransferases: To improve the assay method of ganglioside sialyltransferase activity, we used pryridylamine-labeled oligosaccharides as substrate.These fluorescent substrates were well separated in HPLC and were applicable in sialyltransferase assay. Ganglioside was digested by endoglycoceramidase and released oligosaccharide was labeled by pyridylamine. Sialyltransferase was partially purified from membrane fraction of rat liver Golgi apparatus. Pyridylamine labelled GM3-oligosaccharide was good substrate for GD3 synthase as native GM3 gangliosede. But, Pyridylamine labelled oligosaccharide of CDH was poor substrate for GM3 synthase. Detergent requirment for full activity of GD3 synthase was reduced suggesting that detergent act in part not only as solubilizer of enzyme but also raise availability of glycolipids[2] P … More hoto-affinity labeling of sialyltransferase: Photoactive diazilin derivatives of lactosylceramide and CMP-NeuAc which were the substrate of sialyltransferase (GM3 synthase). These compounds were good substrates and had high affinity to GM3 synthase, respectively. Some molecules were specifically labeled by these compounds and detected by SDS-PAGE autoradiography.[3] Characterization and biosynthesis of gangliosides in developing Xenopus laevis: Change of ganglioside species during early development of Xenopus laevis were studied. Major ganglioside in oocyte was GalNAc-GM1b. There is two possible pathways for in vivo synthesis of GalNAc-GM1b. UDP-GalNAc : GM1b beta1-3 N-acetylgalactosaminyl transferase activity was only detected in Xenopus membrane fraction. These suggest that GalNAc-GM1b was synthesized via GM1b from gangliotetraosylceramide in Xenopus. Dramatical elevation of level of GalNAc-GM1b and GM3 was observed after fertilization. Several lines of evidence suggest that alpha2-3 sialyltransferase activity was elevated during this stage. Less