Solid-phase substrate yielding soluble radioisotopically labeled products upon hydrolysis by a glycoaminoglycan endoglycosidase

A solid phase substrate which yields soluble radioisotopically labeled products upon hydrolysis by a glycosaminoglycan endoglyco­sidase and methods of producing said substrate are comprised in the present invention. The solid phase substrate comprises glycosaminoglycan bearing labeled substances bound to amino groups. The labeled glycos­aminoglycan substrate is reductively aminated at its reducing terminal end to produce an amine-terminus. The substrate is further coupled to an amino-reactive solid matrix through its amine-terminus. A method of producing the solid phase substrate comprises the steps of: at least partially N-desulfating or N-deacylating a glycosaminoglycan; labeling at least partially N-deacylated or N-desulfated glycosaminoglycan with a substance yielding detectable signals to produce labeled glycosaminoglycan; completely N-acylating the labeled glycosaminoglycan with acyl anhydride or acyl halide; reductively aminating a reducing terminal end of said labeled glycosaminoglycan to produce labeled amine-­terminal glycosaminoglycan; and coupling, through its terminal amine, the labeled amine-terminal glycosamino­glycan to an amino-reactive solid phase support to produce the solid phase substrate. The solid phase substrate is usable to detect metastatic tumors by measurement of serum heparanase levels. The potential metastases of a tumor may also be determined by its heparanase levels.