Regulation of glycolipid expression and its disorder

对合成具有生物活性的神经节苷脂的唾液酸转移酶进行了分离和鉴定。[1]高灵敏度、非放射性的唾液酸转移酶活性测定方法：为了改进神经节苷脂唾液酸转移酶活性测定方法，我们采用吡啶胺标记的寡糖作为底物，这些荧光底物在HPLC中分离良好，适用于唾液酸转移酶活性测定。神经节苷脂经神经酰胺糖苷内切酶消化后释放的寡糖经吡啶胺标记。从大鼠肝高尔基体膜组分中部分纯化了唾液酸转移酶。吡啶胺标记的GM 3-寡糖作为天然GM 3神经节苷脂是GD 3合成酶的良好底物。而吡啶胺标记的CDH寡糖是GM 3合成酶的不良底物。GD 3合酶完全活性所需的去污剂减少，表明去污剂不仅部分地作为酶的增溶剂，而且还提高糖脂的可用性[2]。 ...更多信息 唾液酸转移酶的光亲和标记：乳糖神经酰胺和CMP-NeuAc的光敏二嗪衍生物，其是唾液酸转移酶（GM 3合酶）的底物。这些化合物都是很好的底物，对GM 3合成酶有很高的亲和力。一些分子被这些化合物特异性标记，并通过SDS-PAGE放射自显影检测。[3]非洲爪蟾发育过程中神经节苷脂的生物合成与表征：研究了非洲爪蟾早期发育过程中神经节苷脂种类的变化。卵母细胞中主要的神经节苷脂是GalNAc-GM 1b。GalNAc-GM 1b的体内合成有两种可能的途径。UDP-GalNAc：GM 1b β 1 -3 N-乙酰氨基半乳糖转移酶活性仅在爪蟾膜组分中检测到。这表明GalNAc-GM 1b是由非洲爪蟾的神经节四糖基神经酰胺通过GM 1b合成的。受精后，GalNAc-GM 1b和GM 3水平显著升高。多项证据表明，α 2 -3唾液酸转移酶活性在此阶段升高。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