The biosynthesis of chondroitin-sulfate protein complex.

Abstract

A preparation of minced embryonic chicken cartilage catalyzes the in vitro incorpora-tion of serine-C14, acetate-C14, and inorganic sulfate-S35 into chon-droitin sulfuric acid. Puromycin inhibits the incorporation of all 3 compounds into polysaccharide: serine > sulfate > acetate. 6-Diazo-5-oxonorleucine also inhibits the incorporation of all 3 compounds into polysaccharide: acetate > sulphate > serine. The inhibition by 6-diazo-5-oxonorleucine is reduced by addition of glucosamine. Puromycin has no inhibitory effect on nucleotide hexosamine biosynthesis, and neither puromycin nor 6-diazo-5-oxonorleucine has a marked effect on the incorporation of hexosamine into polysaccharide, catalyzed by a cell-free system. These observations are consistent with a biosynthetic mechanism which involves addition of carbohydrate units to preformed protein to yield a protein-polysaccharide complex.