Preparation of Various Lysogangliosides Including Lyso-Fucosyl GM1 and Delayed Extraction Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometric Analysis

抄録

Our rapid method of microwave-mediated saponification for preparing lysoglycosphingo-lipids from their parent glycosphingolipids was also able to prepare lysogangliosides or modified lysogangliosides, which were identified by delayed extraction matrix-assisted laser desorption ionization time-of-flight mass spectrometric (DE MALDI-TOF MS) analy-sis. When GM3, GM2, and GM1 isolated from adult human brain gangliosides were subjected to the saponification, GM3 was found to give rise to only lyso-GM3 containing de-N-acetylneuraminic acid (de-N-acetyl lyso-GM3), whereas the GM2 produced both lyso-GM2 and the de-N-acetyl compound, and GM1 also gave both lyso-GM1 and the de-N-acetyl compound. In the saponification of GM1 and GD1a, isolated from rat brain gangliosides, GM1 similarly produced both lyso-GM1 and the de-N-acetyl compound, but GDIa was found to give rise to both dehydrated de-N-monoacetyl and dehydrated de-N-di-acetyl lyso-GD1a. However, the saponification of the GM1 fraction isolated from porcine brain gangliosides gave rise not only to both lyso-GM1 and the de-N-acetyl compound, but also unexpectedly to both lyso-fucosyl GM1 and its de-N-acetyl compound. The untreated GM1 fraction was examined by TLC and DE MALDI-TOF mass spectrometry, and proved to contain fucosyl-GM1. The DE MALDI-TOF MS analysis of the prepared lyso-gangliosides showed that their long chain bases consisted of d18:1 and d20:1 sphingosines in various ratios reflecting those of the different mammalian brain gangliosides.