Partial primary structure of a fibrinogenase from the venom of the snake Lachesis stenophrys.

The partial primary structure of an Mr 24,000 non-haemorrhagic metalloproteinase isolated from the venom of the snake Lachesis stenophrys has been determined. The native proteinase was resistant to Edman degradation exhibiting the N-terminal blockade. The pyridylethylated or native proteinase was chemically and enzymatically fragmented and the obtained peptides were separated by gel or reversed-phase chromatography, and sequenced. The metalloproteinase from Lachesis stenophrys contains a putative zinc-chelating sequence HELGHNLGMKH, characteristic for the reprolysin family of zinc-metalloproteinases. It contains six cysteine residues in the standard positions for this group of proteins suggesting the same disulfide bonding. Interestingly, it has almost identical sequence as the metalloproteinase from Lachesis muta muta, LHF-II, which is, however, haemorrhagic. The main structural differences between the two molecules were found in their N-terminal parts and in glycosylation. As the substrate-binding regions of both proteinases are practically identical, we suggest that the absence of haemorrhagicity in Lachesis stenophrys enzyme is due to its lower affinity for the matrix proteins and not due to different substrate specificity.