Matrix optimization for matrix-assisted laser desorption/ionization mass spectrometry of oligosaccharides from human milk

✍ Scribed by Pfenninger, Anja; Karas, Michael; Finke, Berndt; Stahl, Bernd; Sawatzki, Günther

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 124 KB
• Volume: 34
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/(sici)1096-9888(199902)34:2<98::aid-jms767>3.0.co;2-n

✦ Synopsis

Neutral and acidic oligosaccharides from human milk were analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI/MS). These experiments require suitable matrices; their selection and particularly their preparation protocols must be optimized. Important criteria are sensitivity, reproducibility, tolerance against impurities and resolution over a wide mass range. For analytical investigations of these oligosaccharides, containing labile fucosylated and sialylated components, another property of a matrix becomes a significant factor, namely the influence on ion stability and the extent of (metastable) fragmentation. The experience gained with the MALDI/MS of neutral and acidic oligosaccharides is summarized taking into account different intentions of measurement and typical problems, such as impurities after enzymatic treatment. For a rapid screening of an oligosaccharide sample, superior results were obtained with a new preparation technique using 5-chloro-2-mercaptobenzothiazole (CMBT) as the first layer for 2,5-dihydroxybenzoic acid. For structural analysis by post-source decay, CMBT as the first layer for 3-aminoquinoline is a favoured preparation protocol, because extensive fragmentation is achieved. For acidic oligosaccharides, a special preparation protocol makes it possible to determine the number of sialic acids by inducing highly effective cationization. Matrix-assisted laser desorption/ionization mass spectrometry; matrices; oligosaccharides; post-source decay.