Isolation and characterisation of serine proteases and metalloproteases from the venom of African puff adders

Abstract

AbstractThe puff adder (Bitis arietans) is a highly venomous viperid snake responsible for many fatalities in Africa, yet despite this there have been few comprehensive analyses of its venom proteins, particularly of the proteases that play a key role in envenoming. This study set out to isolate and characterise the most abundant serine proteases and metalloproteases found in venoms of puff adders obtained from Nigeria, Tanzania and Kenya. All three contained both classes of protease, but there were clear regional differences in the types of protease and their activities. Prominent in all three venoms was an SVMP PII-a. This protease varied in degree of glycosylation between the three sources, and also in its activity. The protease isolated from Tanzanian venoms, which was non-glycosylated, proved to be highly potent, and very destructive towards laminin in particular. The SVMP PIII content of the three venoms was quite low, but in some Kenyan venoms a prominent 68 kDa SVMP PIII was found which has a novel non-covalent dimeric structure and was strongly gelatinolytic, an activity that was not observed in any of the other SVMPs identified here. The Nigerian venoms were rich in an interesting set of serine proteases (SVSPs), the main forms of which were isolated and characterised. Two distinct groups were identified: trypsin-like acidic SVSPs and chymotrypsin-like basic SVSPs, each with different activities. The acidic SVSP is responsible for the gelatinase activity observed in the Nigerian venom, which is a novel form of activity for SVSPs. This regional diversity in venom protease activities is discussed with reference to the implications it will have in the development of therapeutic interventions.