Serine protease inhibitors of North American leeches.

Serine protease inhibitors in extracts from three North American leeches, Nephelopsis obscura, Erpobdella punctata and Hemopis marmorata have been separated by anion exchange chromatography and the activity pattern against human granulocyte elastase and porcine chymotrypsin and trypsin determined. All three leech species contained a major peak with anti-trypsin activity, but Hemopis was unique in that the trypsin inhibitor was equally active against chymotrypsin. Nephelopsis was rich in anti-elastase activity of two types, one which was also active against chymotrypsin, and one which was a specific elastase inhibitor. Erpobdella contained inhibitors against elastase and chymotrypsin but with major activity against the latter.