Analysis of oligosaccharide epitopes of meningococcal lipopolysaccharides by fast-atom-bombardment mass spectrometry.

A mass-spectrometric approach is presented for the analysis of the structures of lipopolysaccharide-derived oligosaccharides, which are frequently difficult to define by classical methods since they contain chemically labile components. The method involves f.a.b.-m.s. of the oligosaccharides, their peracetylated and permethylated derivatives, their deuterioacetylated and methylated analogues, and the fragments obtained during graded methanolysis of the methylated analogues. Data obtained from two representative meningococcal LPS oligosaccharides define the sequence, patterns of branching, and the extent and location of the phosphorylethanolamine and O-acetyl substituents.