Connective tissue activation XXXVIII: heparin/heparanase activity of human platelets resides in a high molecular weight protein, not in connective tissue activating peptide III.

Abstract

OBJECTIVE: Connective tissue activating protein-III (CTAP-III), with molecular weight 9278 Da and isoforms including CTAP-III des 1-15 (neutrophil activating peptide-2, NAP-2) and other amino terminal deletion isoforms, has been isolated from human platelets and characterized. Platelets have also been shown to possess significant heparin/heparanase activity. We investigated whether human platelet heparin/heparanase activity derives from CTAP-III. METHODS: Radial immunodiffusion measurement showed substantial amounts of CTAP-III in plasma from outdated platelet packs. A convenient method for measurement of heparin/heparanase activity is described, and with this method platelet associated plasma was investigated for heparin/heparanase activity assayed against 3H-heparin and 35S-heparan sulfate. RESULTS: Removal of CTAP-III from platelet associated plasma with an immunospecific immunoaffinity column did not remove the heparin/heparanase activity from the plasma. Highly purified CTAP-III eluted from an immunospecific affinity column lacked heparin/heparanase activity. CONCLUSION: Human platelet heparin/heparanase activity resides not in CTAP-III but in a protein or proteins with molecular weight >/= 55 kDa.