FIGURE 3.

Analysis of phospho-oligosaccharides purified from glycogen by MALDI-TOF mass spectrometry. A 1-μl aliquot of phospho-oligosaccharide solution (1 mm in phosphate ester), prepared by the TCA (A) or KOH (B) protocol was analyzed using 2,4,6-trihydroxyacetophenone matrix in negative ion mode. MALDI spectra are shown in which a series of glycogen phosphate peaks from both preparations was detected. The main signals observed are series of glucose oligomers with one mole of phosphate, starting with three hexose units. a.u., absorbance units.