The Nature of Sulphation of Uronic Acid‐containing Glycosaminoglycans Catalysed by Brain Sulphotransferase

Abstract —A sulphotransferase system of rat brain catalyses the transfer of sulphate from 3′‐phosphoadenosine 5′‐phosphosulphate to the low‐sulphated glycosaminoglycans isolated from normal adult human brain. These were shown to be precursors of higher‐sulphated glycosaminoglycans by DEAE‐Sephadex column chromatography and paper electrophoresis. Nitrous acid degradation and mild acid hydrolysis of enzymically‐sulphated fractions further confirmed the presence of heparan sulphate in human brain. A partially purified sulphotransferase preparation was obtained from neonatal human brain using chondroitin‐4‐sulphate as sulphate acceptor. This sulphotransferase catalyses the transfer of sulphate to the various uronic acid containing glycosaminoglycans. Heparan sulphate was the best sulphate acceptor followed by dermatan sulphate, N‐desulphoheparin, chondroitin‐4‐sulphate and chondroitin‐6‐sulphate in decreasing order. Sulphotransferase obtained from 1‐day‐old rat, rabbit and guinea pig brain also had the same pattern of specificity towards various sulphate acceptors. This sulphotransferase catalyses both N‐sulphation and O‐sulphation. Studies on the sulphotransferase obtained from both rat and human brain of various age groups indicate that the ratio of N‐sulphation: O‐sulphation decreases as the brain matures.