Purification of a fragment obtained by autolysis of a PIIIb-SVMP from Bothrops alternatus venom

Snake Venom Metalloproteinases (SVMPs) represent 43.1% of the components in Bothrops alternatus venom and play an important role in envenomation. Disintegrins and disintegrin-like domains are released by proteolytic processing of PII and PIII classes of SVMPs respectively and are potent inhibitors of integrin-ligand interaction. Baltergin is a PIIIb-SVMP isolated from this venom and able to undergo autolysis in vitro, giving rise to a stable disintegrin-like/cystein-rich fragment (baltergin-DC). Conditions of baltergin autolysis were adjusted in order to carry out the purification of baltergin-DC and its effect on cell adhesion was studied. Autolysis was maximal at 37 °C and a pH range of 7.0-8.0. Baltergin-DC amino-terminal sequence begins with IISPPVCGNELLEVGEECDCGTPENCQNECCDAATC, which shows a high degree of homology with other disintegrin-like proteins. Baltergin and purified baltergin-DC were both able to inhibit C2C12 adhesion to fetal bovine serum (FBS) coated plates, indicating that a non-catalytic process is involved, probably mediated by binding to membrane integrins. Baltergin-DC, lacking proteolytic action, becomes an attractive molecule for future studies on blocking integrin-ligand interactions.