Heparan Sulfate Disaccharide Analysis in Mice

2-Aminoacridone (AMAC) and sodium cyanoborohydride were purchased from Sigma-Aldrich (St. Louis, MO, USA). Eight ¹³C-labeled heparan sulfate disaccharide internal standards and ¹³C-labeled polysaccharide (NSK5P) were synthesized as described previously.^{8 (link)} Eight unlabeled native disaccharide standards were purchased from Iduron (Manchester, UK). Recombinant heparan lyase I, II, and III were expressed in E. coli and purified by a Ni–agarose column. DEAE-Sepharose Fast Flow resin was obtained from GE Healthcare (Chicago, IL, USA). Formalin-fixed paraffin-embedded (FFPE) mice tissue slides sectioned in the coronal plane at 5 μm thickness were prepared at the core facility of the University of North Carolina at Chapel Hill (Chapel Hill, NC, USA). Each slide contains 2–3 sections. A Pierce BCA Protein Assay Kit was purchased from Thermo Fisher Scientific (Waltham, MA USA). All reagents and chemicals were LC grade or LC-MS grade.