Inhibition of human chymase by suramin

Chymase is a chymotrypsin-like protease localized in mast cells in complexes with heparin. In the present study, we demonstrated that suramin, a hexasulfonated naphthylurea used as an anti-cancer drug, inhibits the activity of purified human chymase in vitro. The inhibition was ionic-strength-dependent. It was observed that suramin competed with heparin-Sepharose gel for binding to chymase and the inhibition of chymase activity by suramin was partially impaired by heparin. Our results show that suramin may become a prototype of a new type of chymase inhibitor because of its unique character.