Sulphamidase

Sulphamidase is one of four lysosomal proteins whose deficiency clinically manifests as Sanfilippo syndrome. Deficiency of sulphamidase results in the lysosomal storage of the glycosaminoglycan (GAG) heparan sulphate (HS) and is termed mucopolysaccharidosis type IIIA (MPS IIIA). Sulphamidase catalys es the hydrolysis of an N-linked sulphate from the nonreducing terminal glu cosaminide residue of HS (Fig. 1). It is unique among the known lysosomal s ulphatases involved in GAG degradation in that it is an N-sulphatase, all t he others being O-sulphatases. Purification of sulphamidase from human live r has facilitated the amino-terminal sequencing of the protein and hence th e isolation of cDNA and genomic clones for sulphamidase. This has in turn m ade possible a range of further studies aimed at better diagnosis, treatmen t and understanding of MPS IIIA. (C) 1999 Elsevier Science Ltd. All rights reserved.