Human umbilical cord hyaluronate neutral sugar content and carbohydrate-protein linkage studies

Paper chromatography of neural sugars and gas chromatography of their aldononitrile acetates indicated the presence of fucose, arabinose and a small amount of glucose in purified human umbilical cord hyaluronate. The molar ratios of serine, threonine and aspartic acid to neural sugars were not unity, suggesting the non-involvement of the neutral sugars and the amino acids in a carbohydrate-protein linkage. The same was indicated by an increase in the percentage of the aforementioned amino acids and by the absence of sugar alditols in umbilical cord hyaluronate reduced with NaBH₄-PdCl₂, after alkali treatment. This reduction caused a decrease in the intrinsic viscosity and molecular weight to about one-half and an appreciable decrease in the specific rotation of hyaluronate, suggesting a separation of the two antiparallel chains of the double helical hyaluronate. The umbilical cord hyaluronate contained bound silicon and it is possible that this bound silicon may cross-link the two chains at interspersed intervals through the uronic acid moiety and/or through neutral sugars.