Bacterial expression and functional reconstitution of human heparanase.

Human heparanase is a heparan sulfate degrading enzyme located in the extracellular matrix playing a decisive role in angiogenesis and tumor metastasis. Translated as a 65 kDa inactive prae-form, the protein is processed into an 8 kDa and a 50 kDa subunit which form a non-covalently associated active heterodimer. We have expressed the two subunits separately in Escherichia coli which yielded active human heparanase upon reconstitution. The two purified subunits folded independently and secondary structure analysis by far-UV CD spectroscopy gave 33.1/11.1% α/β content for the 50 kDa subunit and 6.9/49% α/β content for the 8 kDa subunit. This heparanase expression system is easy and can be used for efficient screening for enzyme inhibitors.