Structural and immunochemical analysis of three alpha-limit dextrin oligosaccharides.

Complete structures are described for three urinary oligodextrins from one patient with type II and one patient with type III glycogen storage disease. GLC-MS, direct probe MS, and 1H NMR demonstrate two heptasaccharides and one hexasaccharide containing only alpha 1-4 and alpha 1-6 linkages. The observation that all three oligosaccharides were present in urine of both patients and the occurrence of alpha 1-4 and alpha 1-6 linkages in characteristic sequences indicates that the oligodextrins are limit dextrins derived from alpha-amylolytic degradation of glycogen. The binding affinities of the oligodextrins for a monoclonal antibody (401/6) raised against Glc alpha 1-6Glc alpha 1-4Glc alpha 1-4Glc, were determined by frontal analysis. The highest affinity was exhibited by Glc alpha 1-6Glc alpha 1-4Glc alpha 1-4Glc followed by the two heptasaccharides and the hexasaccharide. The results from quantitative affinity measurements agree with results of structural analysis by physical methods in that all oligodextrins containing the nonreducing terminal sequence, Glc alpha 1-6Glc alpha 1-4Glc . . . , are specifically bound by the antibody with similar affinities, but the affinity is somewhat higher for chains containing the tetrasaccharide sequence Glc alpha 1-6Glc alpha 1-4Glc alpha 1-4Glc at the nonreducing terminal. Utilization of affinity methods offers clear advantages for isolation and characterization of oligosaccharides with very similar structures.