Heparanase

Definition

Heparanase is a mammalian enzyme (endo-β-glucuronidase) degrading heparan sulfate (HS), a ubiquitous strongly anionic linear polysaccharide associated with the cell surface and extracellular matrix (ECM) of a wide range of cells of vertebrate and invertebrate tissues. The enzyme cleaves glycosidic bonds in HS with a hydrolase mechanism and is thus distinct from bacterial eliminases, called heparinase and heparitinase. The heparanase enzyme facilitates cell migration and egress from blood vessels and hence plays a role in tumor metastasis, angiogenesis, inflammation, and autoimmunity. Heparanase activity has been identified in a variety of human tumors (i.e., melanoma; carcinoma of the breast, liver, colon, prostate, and pancreas; myeloid leukemia) and certain normal cells (i.e., cytotrophoblasts, platelets, neutrophils, activated T lymphocytes). HS chains (Mr ∼ 30,000) are cleaved by heparanase at only a few sites, resulting in HS fragments of still appreciable size (Mr ∼...