Structures and biological activities of novel phosphonoglycosphingolipids.

本研究鉴定了海腹足动物黑黑的一种主要的神经纤维磷脂的化学结构和组织学定位。FGL-IIb的化学结构：采用气相色谱-质谱、核磁共振、过甲基化等化学方法确定其完整结构为3,4-0-（1-羧基乙基）Ga1 1 3GalNAc 1 3[Fuc 1 2](2-氨基乙基磷酸1 6)Ga1 1 4Glc 1 1-神经酰胺。这是迄今为止在动物中报道的第一个含有鞘脂的丙酮酸。FGL-IIb的基本结构与我们报道的海芹皮肤三种主要的磷酸糖鞘脂相同，即N-Ac半乳糖胺基1- 3 -乳糖-1 -1神经酰胺。分子中的丙酮酸可能使FGL-IIb比我们鉴定的其他磷酸糖鞘脂更具酸性。FGL-IIb和免疫化学相关糖脂的组织分布：兔培养抗FGL-IIb抗血清，用HRP染色法进行免疫化学和免疫组织化学研究。神经纤维、神经节和皮肤的神经束染色。神经细胞体、神经细胞等其他成分未见染色。FGL-IIb对抗血清的反应性通过酯化反应被消除，失去的活性通过皂化反应恢复。这表明FGL-IIb的丙酮酸的游离羧基与FGL-IIb的抗原性有关。除FGL-IIb外，TIC上的抗血清还检测到在海兔神经纤维中发现的FGL-I、FGL-IIa、FGL-V和F-9等磷酸糖鞘脂，表明这些糖脂与FGL-IIb具有相同的抗抗体表位。用氯仿-甲醇混合物对组织进行预处理，完全消除了神经束的染色。这些结果表明，只有海兔组织的神经束中含有像FGL-IIb这样的强酸性糖脂，说明这些糖脂具有一定的神经生物学意义。

In the present study, chemical structure and histohogical localization of a major phosphonoglycosphingolipid of nerve fibes of Aplysia kurodai, a sea gastropod, were identified.1. Chemical structure of FGL-IIb: The complete structure was determined as 3,4-0-(1-carboxy-ethylidene)Ga1 1 3GalNAc 1 3[Fuc 1 2](2-aminoethylphosphony1 6)Ga1 1 4Glc 1 1-ceramide using GC-MS, NMR and chemical methods including permethylation etc. This is the first pyruvate containing sphingolipid so far reported in the animal. The basic structure of FGL-IIb is the same with that reported by us for the three major phosphonoglycosphingolipids of the skin of Aplysia, namely N-Ac galactosaminyl 1 3lactosy1-1 ceramide. Pyruvate in the molecule may make FGL-IIb more acidic than other phosphonoglycosphingolipids identified by us.2. Tissue distribution of FGL-IIb and immunochemically related glycolipids: Anti FGL-IIb antiserum was raised in the rabbit and this polyclonal antiserum was used for immunochemical and immunohistochemical studies with HRP staining. Narve bundles in the nerve fibers, ganglia and skin were stained. Other components including nerve cell bodies and neuropil were not stained at all. The reactivity of FGL-IIb to the antiserum was abolished by esterification of FGL-IIb and the lost activity was recovered by saponifiction. This indicates that free carboxyl of the pyruvic acid of FGL-IIb is responsible for the antigenicity of FGL-IIb.Besides FGL-IIb, other phosphonoglycosphingolipids identified in the nerve fiber of Aplysia as FGL-I, FGL-IIa, FGL-V and F-9 were also stained with the antiserum on TIC indicating that these glycolipids share the same epitope with FGL-IIb against the antibody. Pretreatment of tissues with chloroform-methanol mixture completely abolished the staining of nerve bundles.These results reveal that only the nerve bundles in Aplysia tissues contain very acidic glycolipids as FGL-IIb, indicating some neurobiological significances of these glycolipids.