Stimulation of glycosaminoglycan sulfotransferase from chick embryo cartilage by basic proteins and polyamines

Abstract

A soluble glycosaminoglycan sulfotransferase (3′-phosphoadenylylsulfate: chondroitin 4′-sufotransferase, EC 2.8.2.5) from chick embryo cartilage has been prepared free from endogenous acceptor. The reaction with this enzyme preparation was stimulated by basic proteins and polyamines, the degree of stimulation being dependent on the chemical nature of both basic compounds and acceptor glycosaminoglycans. A maximum stimulation was obtained when protamine (basic compound) and chondroitin (acceptor) were involved in the reaction mixture at a molar ratio of protamine to repeating disaccharide units of chondroitin, 1 : 100. The stimulation of sulfotransferase activity by basic substances was much higher than that by Mn 2+. However, incrasing the Mn 2+ concentration immediately reduced the stimulation by basic substances. The K m value for 3′-phosphoadenosine 5′-phosphosulfate of the sulfotransferase, when chondroitin was used as acceptor, was 1 · 10 −6 M in the presence of 25 μg/ml protamine, compared to 2 · 10 −5 M in the absence of protamine. These observations indicate that the basic proteins and polyamines may interact with acceptor polysaccharide, thereby causing an increase in the affinity of the enzyme toward 3′-phosphoadenosine 5′-phosphosulfate.