1H nuclear-magnetic-resonance spectra of the methyl group of the acetamido moiety and the structure of acid glycosaminoglycans in solution

The 1H resonances of the methyl group in the acetamido moiety of several types of glycosaminoglycans are reported at 300 MHz in 2H2O. Dermatan sulphates with various L-iduronate/D-glucuronate ratios are compared with chrondroitin sulphates with various contents and positions of substitution of sulphate esters. Hyaluronate oligomers are compared with 2-acetamido-2-deoxy-D-glucose, and with heparan sulphate and keratan sulphate. The major determinant of the chemical shift of the acetamido methyl resonance is the closeness of approach between carboxy groups and the acetamido group, in agreement with chemical evidence based on periodate-oxidation kinetics.