Oligosaccharides structural isomeric

The CFR 21 part 11 compliant software newly released by Convergent Bioscience makes imaged cIEF a viable technique for use in QC environments for release testing of therapeutic proteins or antibody molecules. i-cIEF has also been used heavily for characterization of protein modifications such as deamidation and isomerization, as well as oligosaccharide structure analysis. ... 

Another example of the high selectivity of a latexed anion exchanger for the analysis of structurally isomeric oligosaccharide side chains of a glycoprotein is the chromatogram in Fig. 3-121. It shows the separation of mannose hexamers with terminal N-... 

A. Pfenninger, M. Karas, B. Finke, and B. Stahl, Structural analysis of underivatized neutral human milk oligosaccharides in the negative ion mode by nano-electrospray MSn (Part 2 Application to isomeric mixtures), J. Am. Soc. Mass Spectrom., 13 (2002) 1341-1348. 

Compound 11 has been isolated from the urine of patients suffering from GM,-gangliosidosis52 64,643 or from64 65 Morquio syndrome type B. This reducing decasaccharide is isomeric with oligosaccharide 10. It contains three N-acetyllactosamine units, the third unit being attached to 0-6 of Man-4. This structure is denoted as a tri -antennary oligosaccharide. 

Fig. 15. — Structural-reporter-group Regions of the Resolution-enhanced, 500-MHz, H-N.m.r. Spectrum of Compound 14. [The bold-foce numbers in the spectrum refer to the corresponding residues in the structure. Signals of corresponding protons in the a and /3 anomer of 14, occurring in this anomeric mixture in the ratio of 2 1, coincide, unless otherwise indicated. The relative-intensity scale of the N-aeetyl-proton region (see insertion) differs from that of the other part of the spectrum, as indicated. In addition to 14, the sample contained a small proportion of a positionally isomeric oligosaccharide that possesses GlcNAc-7 instead of -9, as follows. This can be inferred from the signals marked by asterisks.

Reaction monitoring and structure determination have often used the more reliable off-bead analytical characterization. Isomeric oligosaccharides have the same MW, thus hampering MS techniques, and their NMR spectra are quite complex. Nevertheless, examples of significant % MAS NMR spectra of resin-bound saccharides have been reported (185). 

UltrafleXtreme (Bruker). Oligosaccharides were labeled on-target with PHN without purification. All ions are [M -I- Naf. Not all isomeric structures are shown [E. Lattova, unpublished data]. 

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