Chigorno V, Valsecchi M, Sonnino S
Study Center for the Functional Biochemistry of Brain Lipids, Department of Medical Chemistry and Biochemistry, The Medical School, University of Milan, Milano, Italy.
Acta Biochim Pol. 1998;45(2):385-92.
Preparation of radioactive GM3 species containing isotopically labeled C18 sphingosine or C20 sphingosine is reported and their use for studying some aspects of the sphingolipid biosynthesis in cells is discussed. Human fibroblasts in culture that have only C18 sphingolipids and GM3 as the major gangliosides, were fed with the two radioactive GM3 species. The radioactive gangliosides were taken up by the cells and metabolized. The analyses of the radioactivity metabolic fate, in this model provides the following information. i--About 70-80% of the total catabolic sphingosine is re-cycled for biosynthesis of complex sphingolipids. ii--A small amount of the catabolic C20 sphingosine was re-cycled for biosynthesis of C20 sphingolipids, thus yielding complex lipids that are not naturally present in fibroblast cells. iii--A regulatory step in the biosynthesis of sphingolipid species differring long chain base content, C18 or C20 sphingosine, is in some way involved in the first steps of sphingolipid biosynthesis, and thus plays a decisive role in the availability of the long chain bases.
报道了含有同位素标记的C18鞘氨醇或C20鞘氨醇的放射性GM3种类的制备，并讨论了它们在研究细胞中鞘脂生物合成某些方面的用途。以仅含有C18鞘脂和GM3作为主要神经节苷脂的培养人成纤维细胞为实验对象，用这两种放射性GM3种类进行喂养。放射性神经节苷脂被细胞摄取并代谢。在此模型中对放射性代谢命运的分析提供了以下信息：i - 约70 - 80%的总分解代谢鞘氨醇被重新循环用于复杂鞘脂的生物合成。ii - 少量分解代谢的C20鞘氨醇被重新循环用于C20鞘脂的生物合成，从而产生成纤维细胞中天然不存在的复杂脂质。iii - 鞘脂种类生物合成中的一个调节步骤，其长链碱基含量不同（C18或C20鞘氨醇），在某种程度上参与了鞘脂生物合成的第一步，因此在长链碱基的可用性方面起决定性作用。
