Protamine modulation of sulfotransferase activity from chicken embryo epiphyseal cartilages changes with the degree of sulfation of the acceptor.

The affinity of a chicken embryo epiphyseal cartilage sulfotransferase, whose endogenous acceptor has been removed by protamine, was 10 times greater for partially sulfated chondroitins than for totally desulfated chondroitins, suggesting that the sulfation of these glycosaminoglycans increased sharply after the addition of the first sulfate groups to the polysaccharide. This sulfotransferase was activated by protamine, presenting Michaelis-Menten kinetics when transferring [35S]sulfate from [35S]3'-phosphoadenosine 5'-phosphosulfate to the totally desulfated chondroitin, whereas sigmoidal kinetics was observed when partially sulfated chondroitin 6-sulfate was employed as substrate. This sigmoidal kinetics was attributed to the combined effect of protamine that both activated the enzyme and removed the sulfate acceptor from solution. The effect of other basic substances on the activity of the sulfotransferase was also reported.