Developmental changes in serum UDP-GlcA:chondroitin glucuronyltransferase activity

Bovine, rat, and chicken UDP-GlcA:chondroitin glucuronyltransferase activities in sera during prenatal and postnatal development were systematically measured with polymeric chondroitin as an exogenous acceptor and with UDP-[C-14]GlcA as a donor. The results indicated that the activity changed markedly with develop ment in all species examined. Specifically, the activity was the highest at the middle prenatal stage in the bovine and chicken sera and at the late prenatal stage in the rat serum, and it decreased sharply thereafter in all three species. Although the origin of the serum enzyme has not yet been determined, these changes may reflect developmentally regulated biosynthesis of chondroitin sulfate and also suggest that the glucuronyltransferase could be a regulatory enzyme controlling the expression of chondroitin sulfate.