Hirabayashi Y, Hyogo A, Nakao T, Tsuchiya K, Suzuki Y, Matsumoto M, Kon K, Ando S
Department of Biochemistry, University of Shizuoka, School of Pharmaceutical Sciences, Japan.
J Biol Chem. 1990 May 15;265(14):8144-51.
In addition to ganglioside GM1b, an unusual and extremely minor ganglioside, GD1 alpha, was efficiently isolated from bovine brain by combination of Q-Sepharose and Iatrobeads column chromatographies. In the course of purification steps, the presence of the sialidase-labile ganglioside was proved by a highly sensitive TLC/enzyme-immunostaining method. The structure was characterized by gas-liquid chromatography, permethylation study, sialidase degradation, immunostaining with specific antibodies, fast atom bombardment-mass spectrometry, and proton magnetic resonance spectrometry. The content of the ganglioside was very small (0.016%) in the total gangliosides. This finding suggests that a synthetic pathway of asialo GM1----GM1b----GD1 alpha may exist in mammalian brains. A monoclonal antibody NA-6 that was obtained by immunizing mice with purified GM1b reacted specifically with GM1b but showed no cross-reactivity with other structurally related gangliosides such as GM1a, GD1a, and so on. Using the method of TLC/immunostaining with NA-6, GM1b was found to be strongly expressed during embryonic days 14-17 in chick brains. Thus, it is assumed that extremely minor gangliosides like GM1b and GD1 alpha found in adult brains are characterized as embryonic molecules.
除了神经节苷脂GM1b外，一种不常见且含量极低的神经节苷脂GD1α通过Q-琼脂糖和Iatrobeads柱色谱法相结合，从牛脑中高效分离出来。在纯化步骤中，通过高灵敏度的薄层色谱/酶免疫染色法证实了唾液酸酶敏感型神经节苷脂的存在。其结构通过气液色谱、全甲基化研究、唾液酸酶降解、特异性抗体免疫染色、快原子轰击质谱和质子磁共振光谱进行了表征。该神经节苷脂在总神经节苷脂中的含量非常少（0.016%）。这一发现表明，在哺乳动物大脑中可能存在脱唾液酸GM1→GM1b→GD1α的合成途径。用纯化的GM1b免疫小鼠获得的单克隆抗体NA-6与GM1b特异性反应，但与其他结构相关的神经节苷脂如GM1a、GD1a等没有交叉反应。使用NA-6进行薄层色谱/免疫染色的方法，发现GM1b在鸡胚脑发育的第14至17天强烈表达。因此，可以推测在成体大脑中发现的GM1b和GD1α等含量极低的神经节苷脂具有胚胎分子的特征。
