The tissue content and turnover rates of intermediates in the biosynthesis of glycosaminoglycans in young rat skin

1. The tissue contents of hexose monophosphate, N-acetylglucosamine 6-phosphate, UDP-glucose, UDP-galactose, UDP-N-acetylglucosamine, UDP-N-acetylgalactosamine and UDP-glucuronic acid were determined in the skin of young rats less than 1 day post partum. Tissue-space determinations were used to calculate their average cellular concentrations. 2. The incorporation of [U-¹⁴C]-glucose into the intermediates was recorded with time and their rates of turnover were calculated. The results demonstrated product–precursor relationships along the pathway of hexosamine synthesis and that of hexuronic acid synthesis. The rates of synthesis of UDP-N-acetylhexosamine and UDP-glucuronic acid were 1·5±0·3 and 0·24±0·03mμmoles/min./g. of tissue respectively. These results indicated the average turnover time of the total tissue glycosaminoglycans to be about 5 days.