Summary
Acurhagin, a high-molecular mass hemorrhagic metalloproteinase, was purified from
the crude venom of Agkistrodon acutus using anionexchange and hydrophobic interaction chromatography. Acurhagin is a monomer
with a molecular mass of 51.4 kDa under non-reducing conditions on SDS-PAGE and 48,133
Da by mass spectrometry. Partial amino acid sequence of its metalloproteinase domain
is homologous to other high-molecular mass metalloproteinases from snake venoms. It
preferentially cleaved Aα. chain of fibrinogen, followed by Bβ chain, while γ chains
was minimally affected. Monitored by RP-HPLC, it extensively degraded fibrinogen into
various peptide fragments. In aqueous solution, acurhagin autoproteolyzed to a 30
kDa fragment at 37° C. The N-terminal sequence of the 30 kDa fragment of acurhagin
showed a high homology to those proteins consisting of disintegrinlike and cysteine-rich
domains. Caseinolytic assay showed that the proteinase activity of acurhagin was slightly
enhanced by Ca2+ and Mg2+, but completely inhibited by Zn2+. When treated with metal chelators, acurhagin was completely inactivated. Furthermore,
acurhagin exerts an inhibitory effect on ADP-induced platelet aggregation of plateletrich
plasma in an incubation-time dependent manner. It also impairs collagen- and ristocetin-induced
platelet aggregation by cleaving collagen and vWF, respectively.
Keywords
Snake venom metalloproteinase -
Agkistrodon acutus, fibrinogenase - autoproteolysis - platelet aggregation