Khoo K H, Dell A
Department of Biochemistry, Imperial College of Science, Technology and Medicine, London, UK.
Glycobiology. 1990 Sep;1(1):83-91. doi: 10.1093/glycob/1.1.83.
This paper describes a sensitive strategy employing fast atom bombardment mass spectrometry (FAB-MS) for defining the anomeric configurations of pyranose sugars in oligosaccharides. The method, which is applicable to mixtures of reduced or unreduced oligosaccharides, is based upon FAB-MS analyses of deuteroacetylated derivatives before and after oxidation with chromium trioxide. This reagent, whose potential value in carbohydrate chemistry was first recognized by Angyal and which was subsequently more fully exploited by Lindberg, oxidizes beta-pyranosides to keto-esters leaving alpha-pyranosides largely intact. In this paper we show that the products of chromium trioxide oxidation can be successfully analysed at the microgram level using FAB-MS. The molecular and fragment ions produced in the FAB experiment define the number of sites oxidized and their location in the sequence. For samples which fragment poorly we describe a mild methanolysis procedure, compatible with FAB-MS, which preferentially cleaves the esters formed during the oxidation. Incorporation of an acetolysis step prior to oxidation permits analyses of polysaccharides. This oxidation/FAB-MS strategy should prove valuable in structural analyses of a wide range of biologically important carbohydrates which cannot be isolated in sufficient quantities to permit nuclear magnetic resonance studies.
本文描述了一种灵敏的方法，该方法采用快原子轰击质谱法（FAB-MS）来确定寡糖中吡喃糖的异头构型。该方法适用于还原或未还原的寡糖混合物，基于对用三氧化铬氧化前后的氘代乙酰化衍生物进行FAB-MS分析。这种试剂在碳水化合物化学中的潜在价值首先由安贾尔认识到，随后林德伯格对其进行了更充分的利用，它将β-吡喃糖苷氧化为酮酯，而α-吡喃糖苷基本保持完整。在本文中，我们表明使用FAB-MS可以在微克水平上成功分析三氧化铬氧化的产物。FAB实验中产生的分子离子和碎片离子确定了氧化位点的数量及其在序列中的位置。对于碎片较少的样品，我们描述了一种与FAB-MS兼容的温和甲醇解程序，该程序优先裂解氧化过程中形成的酯。在氧化之前加入乙酰解步骤可以对多糖进行分析。这种氧化/FAB-MS策略在对大量无法分离出足够量以进行核磁共振研究的具有生物学重要性的碳水化合物的结构分析中应具有重要价值。
