Human mononuclear cells contain an endoglycosidase specific for heparan sulphate glycosaminoglycan demonstrable with the use of a specific solid-phase metabolically radiolabelled substrate.

Xyloside-initiated 35SO4(2-)-labelled glycosaminoglycans were isolated from the medium of cultured bovine glomeruli and covalently coupled to Sepharose 4B to construct a solid-phase substrate suitable for the detection of endoglycosidases. The substrate is rendered specific for heparitinase by prior digestion with chondroitin sulphate ABC lyase and is insensitive to proteinase, neuraminidase and hyaluronidase. Normal human mononuclear cells are shown to contain a heparitinase. This enzyme appears to be cell-associated and can be partially purified from human spleen by heparin affinity chromatography.