Analysis of the pharmaceutical preparations of bovine (in blue) and porcine (in red) heparin by 1D 1H NMR spectroscopy at 800 MHz. The signals designated as A1 correspond to H1 of N,6-disulfated α-glucosamine units; B1 and C1 to H1 of N-acetylated and 6-desulfated α-glucosamine units, respectively. These chemical modifications of the α-glucosamine units shift ~0.2 ppm downfield H1 of the neighbor 2-sulfated α-iduronic acid (I1 in the panel). Furthermore, 6-desulfation but not N-acetylation of the α-glucosamine units shift ~0.2 ppm downfield H5 of the same α-iduronic acid units (I5 in the panel). GlcN S-GlcA corresponds to H1 of N-sulfated α-glucosamine linked to β-glucuronic acid and GlcNS3S6S to H1 of N,3,6-trisulfated α-glucosamine units. I1 (deS)-A and I1(deS)-C are H1 of desulfated α-iduronic acid residues linked to N,6-disulfated and N-sulfated α-glucosamine units, respectively.