Riboni L, Sonnino S, Acquotti D, Malesci A, Ghidoni R, Egge H, Mingrino S, Tettamanti G
J Biol Chem. 1986 Jun 25;261(18):8514-9.
A new ganglioside containing an inner ester linkage was extracted from adult brain specimens, obtained at the time of surgery on 51-70-year-old subjects, purified, and analyzed. It contains glucose, galactose, N-acetylgalactosamine, an N-acetylneuraminic acid in the molar ratio 1:2:1:2, but, on ion-exchange chromatography, behaves as a monosialoganglioside. Structural analyses showed its basic neutral glycosphingolipid core to be ganglio-N-tetraose ceramide, carrying a disialosyl residue on the 3-position of internal galactose. Sialidase degradation and chemical analysis of the products obtained after alkaline treatments suggested one sialic acid residue to be involved in an ester linkage. Fast atom bombardment-mass spectrometry indicated the presence of an inner ester linkage between the carboxyl group of the external sialic acid residue and a hydroxyl group of the internal one. On these bases, the new ganglioside can be assumed to be a GD1b in lactonic form. This ganglioside is present only in trace amounts in the brain of infants, but its content increases with age, reaching a value of 3.5% of total sialic acid in 51-70-year-old subjects.
从51至70岁患者手术时获取的成人大脑标本中提取、纯化并分析了一种含有内部酯键的新神经节苷脂。它含有葡萄糖、半乳糖、N-乙酰半乳糖胺、N-乙酰神经氨酸，摩尔比为1:2:1:2，但在离子交换色谱上表现为单唾液酸神经节苷脂。结构分析表明其基本中性糖鞘脂核心是神经节-N-四糖神经酰胺，在内部半乳糖的3位带有一个双唾液酸残基。唾液酸酶降解以及碱处理后产物的化学分析表明一个唾液酸残基参与了酯键连接。快原子轰击质谱表明外部唾液酸残基的羧基与内部唾液酸残基的一个羟基之间存在内部酯键。基于这些，新神经节苷脂可被认为是内酯形式的GD1b。这种神经节苷脂在婴儿大脑中仅微量存在，但其含量随年龄增长而增加，在51至70岁患者中达到总唾液酸的3.5%。
