Venom from southern copperhead snake (Agkistrodon contortrix contortrix). I. Characterization of a protease that preferentially releases fibrinopeptide B.

Using gel permeation chromatography with high performance liquid chromatograph (HPLC), a highly purified preparation of a protease has been obtained from the venom of the southern copperhead snake (Agkistrodon contortrix contortrix). Both gel permeation chromatography with HPLC and sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that it had an apparent Mr of 60,000-64,000. It consisted of a single polypeptide chain. The activity was inhibited by dithiothreitol. It neither induced platelet aggregation nor activated plasma factor XIII. It cleaved fibrinopeptide B at a rate much faster than fibrinopeptide A from fibrinogen. This specificity was steadily lowered when the incubation temperature was elevated from 0 degrees C to 45 degrees C. Fibrinopeptides were released only at neutral pH.